What causes these codes, and how do I get rid of them?
03-01-2003, 07:15 PM
#1
What causes these codes, and how do I get rid of them? What causes these codes, and how do I get rid of them? It looks like the O2 sensor or cat. converter is bad, but not sure.
P0420 Catalyst System Effeciency Below Threshold (Bank 1)
P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
Which sensor is B1? Which cat is B1? Is Bank 1 pass or driverside? Sensor B1 is front (pre-cat) sensor, no? TIA, Shawn
P0420 Catalyst System Effeciency Below Threshold (Bank 1)
P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
Which sensor is B1? Which cat is B1? Is Bank 1 pass or driverside? Sensor B1 is front (pre-cat) sensor, no? TIA, Shawn
03-01-2003, 09:23 PM
#2
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Re: What causes these codes, and how do I get rid of them? This maybe more than you ever wanted to know, but, this is from GM Tech Service.
"DTC P0420
CIRCUIT DESCRIPTION
In order to maintain reasonably low emissions of Hydrocarbons (HC) , Carbon Monoxide (CO) , and Oxides of Nitrogen (NOx) , the Computers and Control Systems system uses a 3-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The PCM monitors this process using Bank 1 HO2S # 2. Bank 1 HO2S # 2, located in the exhaust stream past the 3-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalyst's ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the Bank 1 HO2S # 2 signal will be far less active than the signal produced by Bank 1 HO2S # 1. This indicates that the 3-way catalytic converters oxygen storage capacity is below an acceptable threshold.
When the Conditions for Running this DTC are met, the following conditions occur:
The PCM captures the current rear HO2S rich-to-lean status.
The Air/Fuel ratio transitions from rich to lean, or from lean to rich, depending on the capture rear HO2S rich-to-lean status.
The Air/Fuel ratio transitions a second time opposite the first Air/Fuel ratio transition.
The PCM captures the response time of the front and rear heated oxygen sensors when the Air/Fuel ratio transitions occurred. The response time is the time during which the HO2S goes from below 300 mV to above 600 mV , and from 600 mV to below 300 mV .
The PCM measures the time for the rear HO2S voltage to cross a reference rich-to-lean threshold, minus the time for the front HO2S voltage to cross the same rich-to-lean threshold. The time difference from the front and rear HO2S is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
CONDITIONS FOR RUNNING THE DTC
DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0200, P0300, P0325, P0327, P0332, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0410, P0412, P0418, P0440, P0442, P0443, P0446, P0449, P0500, P0502, P0506, P0507, P0704, P0801, P0803, P1258, P1336, P1415, P1416, and P1441 are not set.
The engine is operating for more than 450 seconds.
The ECT is between 75°C (167°F)-120°C (248°F) .
The IAT is between 18°C (64°F)-80°C (176°F) .
Since the end of the last idle test, the engine speed is more than 1000 RPM for a minimum of 37 seconds for a manual transmission
Since the end of the last idle test, the engine speed is more than 1000 RPM for a minimum of 44 seconds for an automatic transmission
The BARO is more than 74 kPa.
The fuel system is operating in closed loop.
CONDITIONS FOR SETTING THE DTC
The PCM determines that the oxygen storage capability of the catalytic converter has degraded below a calibrated threshold."
"DTC P0420
CIRCUIT DESCRIPTION
In order to maintain reasonably low emissions of Hydrocarbons (HC) , Carbon Monoxide (CO) , and Oxides of Nitrogen (NOx) , the Computers and Control Systems system uses a 3-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The PCM monitors this process using Bank 1 HO2S # 2. Bank 1 HO2S # 2, located in the exhaust stream past the 3-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalyst's ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the Bank 1 HO2S # 2 signal will be far less active than the signal produced by Bank 1 HO2S # 1. This indicates that the 3-way catalytic converters oxygen storage capacity is below an acceptable threshold.
When the Conditions for Running this DTC are met, the following conditions occur:
The PCM captures the current rear HO2S rich-to-lean status.
The Air/Fuel ratio transitions from rich to lean, or from lean to rich, depending on the capture rear HO2S rich-to-lean status.
The Air/Fuel ratio transitions a second time opposite the first Air/Fuel ratio transition.
The PCM captures the response time of the front and rear heated oxygen sensors when the Air/Fuel ratio transitions occurred. The response time is the time during which the HO2S goes from below 300 mV to above 600 mV , and from 600 mV to below 300 mV .
The PCM measures the time for the rear HO2S voltage to cross a reference rich-to-lean threshold, minus the time for the front HO2S voltage to cross the same rich-to-lean threshold. The time difference from the front and rear HO2S is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
CONDITIONS FOR RUNNING THE DTC
DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0200, P0300, P0325, P0327, P0332, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0410, P0412, P0418, P0440, P0442, P0443, P0446, P0449, P0500, P0502, P0506, P0507, P0704, P0801, P0803, P1258, P1336, P1415, P1416, and P1441 are not set.
The engine is operating for more than 450 seconds.
The ECT is between 75°C (167°F)-120°C (248°F) .
The IAT is between 18°C (64°F)-80°C (176°F) .
Since the end of the last idle test, the engine speed is more than 1000 RPM for a minimum of 37 seconds for a manual transmission
Since the end of the last idle test, the engine speed is more than 1000 RPM for a minimum of 44 seconds for an automatic transmission
The BARO is more than 74 kPa.
The fuel system is operating in closed loop.
CONDITIONS FOR SETTING THE DTC
The PCM determines that the oxygen storage capability of the catalytic converter has degraded below a calibrated threshold."
03-02-2003, 02:49 PM
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Re: What causes these codes, and how do I get rid of them? B1 is the driver's side (or only choice if it has S1 (sensor 1) further down in the system after both headers have merged), B2 is passenger. S1 (sensor 1) is pre-cat or in GM speak, "Upstream" and S2 (sensor 2) is post cat or in GM speak "downstream".
What year is your car? The code is the same just how to troubleshoot could vary between years.
What year is your car? The code is the same just how to troubleshoot could vary between years.
03-02-2003, 07:40 PM
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Re: What causes these codes, and how do I get rid of them? My gut feeling is that P0135 caused P0420 and you'll want to fix that first. As a matter of fact, step number 2 for P0420 says to fix all others first. Also, one of the conditions for running the P0420 DTC, states - The PCM captures the response time (the time the HO2S goes from below 300 mV to above 600 mV and from 600 mV to below 300 mV) of the front and rear Heated Oxygen sensors when the Air Fuel ratio transitions occurred. which would coincide with a malfunctioning heating O2 sensor.
P0420
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">DTC P0420 Catalyst System Low Efficiency Bank 1
Circuit Description
In order to maintain a reasonably low emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), the engine controls system uses a three-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and Carbon Dioxide. The catalyst also reduces NOx, converting it to Nitrogen. The PCM monitors this process using Bank 1 HO2S #2. Bank 1 HO2S #2, located in the exhaust stream past the three-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 1 HO2S #2 signal will be far less active than that produced by Bank 1 HO2S #1. This indicates that the three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.
When the conditions for running this DTC are met, the following occurs:
- The PCM captures the current rear HO2S rich/lean status.
- The Air Fuel ratio transitions from rich to lean or lean to rich depending on the capture rear HO2S rich/lean status.
- The Air Fuel ratio transitions a second time opposite the first Air Fuel ratio transition.
- The PCM captures the response time (the time the HO2S goes from below 300 mV to above 600 mV and from 600 mV to below 300 mV) of the front and rear Heated Oxygen sensors when the Air Fuel ratio transitions occurred.
- The PCM measures the time it takes the rear HO2S voltage to cross a reference rich/lean threshold minus the time it takes the front HO2S voltage to cross the same rich/lean threshold. The time difference from the front and rear HO2S is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
Conditions for Running the DTC
- DTCs, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0200, P0230, P0300, P0325, P0327, P0332, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0401, P0404, P0405, P0410, P0412, P0418, P0440, P0442, P0443, P0446, P0449, P0500, P0704, P0801, P0803, P1258, P1336, P1404, P1415, P1416, P1441 and HO2S DTCs not set.
- The engine is operating for longer than 400 seconds.
- The ECT is between 80°C (176°F) 120°C (248°F).
- The IAT is between -15°C (5°F) and 75°C (167°F).
- Engine speed is more than 900 RPM for a minimum of 22 seconds (manual transmission) or 25 seconds (Automatic Transmission) since the end of the last idle test.
- The BARO is more than 74 kPA.
- The fuel system is operating in closed loop.
Conditions for Setting the DTC
The PCM determines the oxygen storage capability of the catalytic converter has degraded below a calibrated threshold.
Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
Conditions for Clearing the MIL/DTC
- The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
If the HO2S parameter is monitored using a scan tool while this diagnostic is running, the HO2S voltages may be fixed low or high.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
4) Before replacing the Three-Way Catalytic Converter, correct any conditions which may have damaged the catalyst.
Step 1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Yes: Go to Step 2
No: Go to Powertrain On Board Diagnostic (OBD) System Check
Step 2
Are any other DTCs set?
--
Yes: Go to the applicable DTC table
No: Go to Step 3
Step 3
Inspect for the following conditions:
-Verify that the three-way catalytic converter is an original equipment part.
-Inspect the three-way catalytic converter for damage (dents, severe discoloration caused by excessive temperature, holes, etc.).
-Insure that the internal three-way catalytic converter rattle caused by damaged catalyst is not present.
-Inspect the exhaust system for leaks, damage, or loose or missing hardware (area from converter to HO2S #2 primarily). Refer to Exhaust System Inspection in Engine Exhaust.
-Insure that the HO2S #1 and the HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust.
Did you find and correct the condition?
--
Yes: Go to Step 5
No: Go to Step 4
Step 4
Replace the catalytic converter. Refer to Oxidation Catalytic Converter Replacement in Engine Exhaust.
Is the action complete?
--
Yes: Go to Step 5
--
Step 5
1) Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2) Idle the engine at the normal operating temperature.
3) Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4) Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Yes: Go to Step 6
No: Go to Step 2
Step 6
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Yes: Go to the applicable DTC table
No: System OK</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">P0135
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">DTC P0135 HO2S Heater Performance Bank 1 Sensor 1
Circuit Description
The powertrain control module (PCM) supplies a bias voltage (approximately 450 mV) on the heated oxygen sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.
The PCM runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, this DTC sets. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.
Conditions for Running the DTC
- DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0200, P0335, P0336, P0351-P0358, P1258 not set.
- The intake air temperature (IAT) and the engine coolant temperature (ECT) are less than 50°C (122°F) and are within 8°C (14.5°F) of each other at engine start-up.
- The ignition voltage is between 10.0 volts and 18.0 volts.
- The AIR, EGR, and the Catalyst diagnostics are not active.
Conditions for Setting the DTC
The HO2S voltage remains between 300 mV and 700 mV for a predetermined amount of time (depends on engine coolant temperature and air flow).
Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
- The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important
- Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
- For any test that requires probing the PCM or component harness connectors, use the J 35616-A connector test adapter kit. Using this kit prevents any damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.
The heater diagnostic only runs on a cold start and runs once per ignition cycle.
An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems.
For an intermittent condition, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2) Allow the engine to cool before performing this test. If the sensor is at the operating temperature the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-700 mV indicates the HO2S heater is inoperative.
3) If more than one HO2S DTC is set, this is a good indication that the HO2S fuse is open. Test all the related circuits going to all the heated oxygen sensors for a short to ground. If all the wiring is OK, it may be necessary to disconnect each HO2S one at a time to locate a shorted sensor.
4) This step verifies whether a B+ supply is available at the sensor.
5) This step verifies whether a ground is available at the sensor.
6) This step verifies whether the HO2S heater element is internally open.
7) Inspect the ignition feed circuits at the Underhood Electrical Center for poor connections.
8) Test the ground circuits for an open if more then one heater DTC sets.
Step 1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Yes: Go to Step 2
No: Go to Powertrain On Board Diagnostic (OBD) System Check
Step 2
Important
Allow the engine to cool for about one half hour before proceeding with this table.
1) Turn OFF the ignition.
2) Install the scan tool.
3) Turn ON the ignition leaving the engine OFF.
4) Monitor the HO2S voltage display on the Engine 1 Data List of the scan tool.
Does the HO2S voltage go from a bias voltage to above or below the specified range?
Specified Range = 300-700 mV
--
Yes: Go to Diagnostic Aids
No: Go to Step 3
Step 3
Inspect the HO2S fuse for an open.
Is the HO2S fuse open?
--
Yes: Go to Step 11
No: Go to Step 4
Step 4
1) Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information .
2) Disconnect the HO2S electrical connector.
3) Probe the ignition feed circuit at the HO2S electrical connector (PCM side) using a J 34142-B test lamp connected to ground (a known good ground. Do not use the HO2S heater ground or the HO2S low circuits).
Does the test lamp illuminate?
--
Yes: Go to Step 5
No: Go to Step 7
Step 5
Connect the J 34142-B test lamp between the HO2S ignition feed and the HO2S heater ground.
Does the test lamp illuminate?
--
Yes: Go to Step 6
No: Go to Step 8
Step 6
Measure the resistance between the HO2S ignition feed and the HO2S heater ground at the HO2S pigtail using a DMM.
Is the HO2S resistance within the specified range?
Specified Range = 3.5-14.0ohms
--
Yes: Go to Step 9
No: Go to Step 10
Step 7
Repair the open in the HO2S ignition feed circuit to the HO2S. Refer to Wiring Repairs in Wiring Systems .
Is the action complete?
--
Yes: Go to Step 12
--
Step 8
Repair the open in the HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?
--
Yes: Go to Step 12
--
Step 9
1) Inspect for a poor connection at the HO2S. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
2) If you find a poor connection, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and repair the condition?
--
Yes: Go to Step 12
No: Go to Step 10
Step 10
Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1 .
Is the action complete?
--
Yes: Go to Step 12
--
Step 11
1) Locate and repair the short to ground in the HO2S ignition feed circuit.
2) Replace the faulty fuse. Refer to Wiring Repairs in Wiring Systems .
Is the action complete?
--
Yes: Go to Step 12
--
Step 12
1) Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2) Idle the engine at the normal operating temperature.
3) Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4) Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Yes: Go to Step 13
No: Go to Step 2
Step 13
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Yes: Go to the applicable DTC table
No: System OK</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">
P0420
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">DTC P0420 Catalyst System Low Efficiency Bank 1
Circuit Description
In order to maintain a reasonably low emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), the engine controls system uses a three-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and Carbon Dioxide. The catalyst also reduces NOx, converting it to Nitrogen. The PCM monitors this process using Bank 1 HO2S #2. Bank 1 HO2S #2, located in the exhaust stream past the three-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 1 HO2S #2 signal will be far less active than that produced by Bank 1 HO2S #1. This indicates that the three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.
When the conditions for running this DTC are met, the following occurs:
- The PCM captures the current rear HO2S rich/lean status.
- The Air Fuel ratio transitions from rich to lean or lean to rich depending on the capture rear HO2S rich/lean status.
- The Air Fuel ratio transitions a second time opposite the first Air Fuel ratio transition.
- The PCM captures the response time (the time the HO2S goes from below 300 mV to above 600 mV and from 600 mV to below 300 mV) of the front and rear Heated Oxygen sensors when the Air Fuel ratio transitions occurred.
- The PCM measures the time it takes the rear HO2S voltage to cross a reference rich/lean threshold minus the time it takes the front HO2S voltage to cross the same rich/lean threshold. The time difference from the front and rear HO2S is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
Conditions for Running the DTC
- DTCs, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0200, P0230, P0300, P0325, P0327, P0332, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0401, P0404, P0405, P0410, P0412, P0418, P0440, P0442, P0443, P0446, P0449, P0500, P0704, P0801, P0803, P1258, P1336, P1404, P1415, P1416, P1441 and HO2S DTCs not set.
- The engine is operating for longer than 400 seconds.
- The ECT is between 80°C (176°F) 120°C (248°F).
- The IAT is between -15°C (5°F) and 75°C (167°F).
- Engine speed is more than 900 RPM for a minimum of 22 seconds (manual transmission) or 25 seconds (Automatic Transmission) since the end of the last idle test.
- The BARO is more than 74 kPA.
- The fuel system is operating in closed loop.
Conditions for Setting the DTC
The PCM determines the oxygen storage capability of the catalytic converter has degraded below a calibrated threshold.
Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
Conditions for Clearing the MIL/DTC
- The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
If the HO2S parameter is monitored using a scan tool while this diagnostic is running, the HO2S voltages may be fixed low or high.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
4) Before replacing the Three-Way Catalytic Converter, correct any conditions which may have damaged the catalyst.
Step 1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Yes: Go to Step 2
No: Go to Powertrain On Board Diagnostic (OBD) System Check
Step 2
Are any other DTCs set?
--
Yes: Go to the applicable DTC table
No: Go to Step 3
Step 3
Inspect for the following conditions:
-Verify that the three-way catalytic converter is an original equipment part.
-Inspect the three-way catalytic converter for damage (dents, severe discoloration caused by excessive temperature, holes, etc.).
-Insure that the internal three-way catalytic converter rattle caused by damaged catalyst is not present.
-Inspect the exhaust system for leaks, damage, or loose or missing hardware (area from converter to HO2S #2 primarily). Refer to Exhaust System Inspection in Engine Exhaust.
-Insure that the HO2S #1 and the HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust.
Did you find and correct the condition?
--
Yes: Go to Step 5
No: Go to Step 4
Step 4
Replace the catalytic converter. Refer to Oxidation Catalytic Converter Replacement in Engine Exhaust.
Is the action complete?
--
Yes: Go to Step 5
--
Step 5
1) Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2) Idle the engine at the normal operating temperature.
3) Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4) Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Yes: Go to Step 6
No: Go to Step 2
Step 6
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Yes: Go to the applicable DTC table
No: System OK</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">P0135
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">DTC P0135 HO2S Heater Performance Bank 1 Sensor 1
Circuit Description
The powertrain control module (PCM) supplies a bias voltage (approximately 450 mV) on the heated oxygen sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.
The PCM runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, this DTC sets. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.
Conditions for Running the DTC
- DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0200, P0335, P0336, P0351-P0358, P1258 not set.
- The intake air temperature (IAT) and the engine coolant temperature (ECT) are less than 50°C (122°F) and are within 8°C (14.5°F) of each other at engine start-up.
- The ignition voltage is between 10.0 volts and 18.0 volts.
- The AIR, EGR, and the Catalyst diagnostics are not active.
Conditions for Setting the DTC
The HO2S voltage remains between 300 mV and 700 mV for a predetermined amount of time (depends on engine coolant temperature and air flow).
Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
- The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important
- Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
- For any test that requires probing the PCM or component harness connectors, use the J 35616-A connector test adapter kit. Using this kit prevents any damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.
The heater diagnostic only runs on a cold start and runs once per ignition cycle.
An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems.
For an intermittent condition, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2) Allow the engine to cool before performing this test. If the sensor is at the operating temperature the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-700 mV indicates the HO2S heater is inoperative.
3) If more than one HO2S DTC is set, this is a good indication that the HO2S fuse is open. Test all the related circuits going to all the heated oxygen sensors for a short to ground. If all the wiring is OK, it may be necessary to disconnect each HO2S one at a time to locate a shorted sensor.
4) This step verifies whether a B+ supply is available at the sensor.
5) This step verifies whether a ground is available at the sensor.
6) This step verifies whether the HO2S heater element is internally open.
7) Inspect the ignition feed circuits at the Underhood Electrical Center for poor connections.
8) Test the ground circuits for an open if more then one heater DTC sets.
Step 1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Yes: Go to Step 2
No: Go to Powertrain On Board Diagnostic (OBD) System Check
Step 2
Important
Allow the engine to cool for about one half hour before proceeding with this table.
1) Turn OFF the ignition.
2) Install the scan tool.
3) Turn ON the ignition leaving the engine OFF.
4) Monitor the HO2S voltage display on the Engine 1 Data List of the scan tool.
Does the HO2S voltage go from a bias voltage to above or below the specified range?
Specified Range = 300-700 mV
--
Yes: Go to Diagnostic Aids
No: Go to Step 3
Step 3
Inspect the HO2S fuse for an open.
Is the HO2S fuse open?
--
Yes: Go to Step 11
No: Go to Step 4
Step 4
1) Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information .
2) Disconnect the HO2S electrical connector.
3) Probe the ignition feed circuit at the HO2S electrical connector (PCM side) using a J 34142-B test lamp connected to ground (a known good ground. Do not use the HO2S heater ground or the HO2S low circuits).
Does the test lamp illuminate?
--
Yes: Go to Step 5
No: Go to Step 7
Step 5
Connect the J 34142-B test lamp between the HO2S ignition feed and the HO2S heater ground.
Does the test lamp illuminate?
--
Yes: Go to Step 6
No: Go to Step 8
Step 6
Measure the resistance between the HO2S ignition feed and the HO2S heater ground at the HO2S pigtail using a DMM.
Is the HO2S resistance within the specified range?
Specified Range = 3.5-14.0ohms
--
Yes: Go to Step 9
No: Go to Step 10
Step 7
Repair the open in the HO2S ignition feed circuit to the HO2S. Refer to Wiring Repairs in Wiring Systems .
Is the action complete?
--
Yes: Go to Step 12
--
Step 8
Repair the open in the HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?
--
Yes: Go to Step 12
--
Step 9
1) Inspect for a poor connection at the HO2S. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
2) If you find a poor connection, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and repair the condition?
--
Yes: Go to Step 12
No: Go to Step 10
Step 10
Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1 .
Is the action complete?
--
Yes: Go to Step 12
--
Step 11
1) Locate and repair the short to ground in the HO2S ignition feed circuit.
2) Replace the faulty fuse. Refer to Wiring Repairs in Wiring Systems .
Is the action complete?
--
Yes: Go to Step 12
--
Step 12
1) Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2) Idle the engine at the normal operating temperature.
3) Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4) Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Yes: Go to Step 13
No: Go to Step 2
Step 13
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Yes: Go to the applicable DTC table
No: System OK</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">
