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The dreaded po131and po151codes

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Old 02-02-2012, 12:53 PM
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Default The dreaded po131and po151codes

My 98 ws6 has been stumbling at mid rpm and if I go full throttle I get the po131 and po151 codes tripped. From what I've read I should clean the mass air and check the wiring on the o2 sensors.

Any one have any other suggestions? Thanks
Old 02-02-2012, 06:01 PM
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Could dirty injectors cause these codes?
Old 02-02-2012, 06:04 PM
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P0131 Heated Oxygen Sensor (Bank 1 Sensor 1) Circuit Low Input
Possible Causes
* Check for air leaks in the Air Induction system (e.g., in the intake manifold)
* Check for air leaks in the exhaust manifold and in the exhaust pipes
* Engine misfire condition present (look for P0300 series codes)
* Fuel system too lean (possible low fuel pressure, water in fuel)
* HO2S signal circuit is shorted to ground
* HO2S has failed (it may be contaminated with fuel, silicone or water)
* PCM has failed
Setting Conditions

* Check for air leaks in the Air Induction system (e.g., in the intake manifold)
* Check for air leaks in the exhaust manifold and in the exhaust pipes
* Engine misfire condition present (look for P0300 series codes)
* Fuel system too lean (possible low fuel pressure, water in fuel)
* HO2S signal circuit is shorted to ground
* HO2S has failed (it may be contaminated with fuel, silicone or water)
* PCM has failed

Lean Test Enable
DTC P0101, P0102, P0103, P0106-P0108, P0112-P0113, P0116-P0118, P0121, P0122, P0123, P0125, P0128, P0200, P0300, P0410-P0446, P0452-P0453, P1258, P1415-P1416 and P1441 not set; engine running in Closed Loop, Intrusive and Scan Tool tests "off", A/F ratio at 14.5-14.8:1, TP angle from 3-70%, and the PCM detected the Bank 1 HO2S-11 signal was less than 200 mv for 165 seconds.
Rich Test Enable
Engine running under the conditions listed above; engine operating in Power Enrichment mode for 1 second, and the PCM detected the Bank 1 HO2S-11 signal was less than 360 mv for 10 seconds.

This code sets in 2 Trip(s).
This code will turn on the MIL (Malfunction Indicator Lamp)
Old 02-02-2012, 06:06 PM
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P0151 Heated Oxygen Sensor (Bank 2 Sensor 1) Circuit Low Input
Possible Causes

* Check for air leaks in the Air Induction system (e.g., in the intake manifold)
* Check for air leaks in the Air Induction system (e.g., in the intake manifold)
* Engine misfire condition present (look for P0300 series codes)
* Fuel system too lean (possible low fuel pressure, water in fuel)
* HO2S connector is damaged (check pins for damage, and for moisture)
* HO2S signal circuit is shorted to ground
* HO2S has failed (it may be contaminated with fuel, silicone or water)
* PCM has failed
Setting Conditions
Lean Test Enable
DTC P0101, P0102, P0103, P0106-P0108, P0112-P0113, P0116-P0118, P0121, P0122, P0123, P0125, P0128, P0200, P0300, P0410-P0446, P0452-P0453, P1258, P1415-P1416 and P1441 not set; engine running in Closed Loop, Intrusive and Scan Tool tests "off", A/F ratio at 14.5-14.8:1, TP angle from 3-70%, and the PCM detected the Bank 2 HO2S-21 signal was less than 200 mv for 165 seconds.
Rich Test Enable
Engine running under the conditions listed above; engine operating in Power Enrichment mode for 1 second, and the PCM detected the Bank 2 HO2S-21 signal was less than 360 mv for 10 seconds.

This code sets in 2 Trip(s).
This code will turn on the MIL (Malfunction Indicator Lamp)
Old 02-02-2012, 06:07 PM
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i'd look for air leaks, and check the mass airflow sensor. also check for exhaust leaks
Old 02-03-2012, 06:18 AM
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Thanks guys ill start there
Old 02-03-2012, 08:29 AM
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Great info, does this apply to all obd II?
Old 02-03-2012, 08:42 AM
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Originally Posted by baalic
Great info, does this apply to all obd II?
the posts i put up were specific to this vehicle, but in general, they can be applied to any obd2 car.

more often than not, the o2 sensors are the victims, rather than the criminals when a code pops, although they can and do go bad.

while i can be an antagonistic bastard sometimes, i try to help people out when i can.
Old 02-04-2012, 04:10 PM
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Is there some where in particular where vaccine leaks develop often? All the hoses I've checked look ok.
Old 02-05-2012, 06:28 PM
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I found my vaccum leak!!!!!!! The hose that comes from the back of the motor had a dime sized hole in it right before it connects to the pcv valve. For now I just took out the pcv valve and capped both ends of the hoses. Took her for a drive and it ran like a top no trouble codes. Thanks for the help guys now all I have to do is replace the hose when I do my intake swap.
Old 02-05-2012, 07:22 PM
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Originally Posted by Ws6power1
I found my vaccum leak!!!!!!! The hose that comes from the back of the motor had a dime sized hole in it right before it connects to the pcv valve. For now I just took out the pcv valve and capped both ends of the hoses. Took her for a drive and it ran like a top no trouble codes. Thanks for the help guys now all I have to do is replace the hose when I do my intake swap.
awesomeness!

this is the first time i've heard of that particular type of problem with a gm product.....the big hole in the pcv hose that is. that very same problem is a stupidly common occurrence on fords. on them it generates p0171, and p0174. on the 4.6 liters, it was ALWAYS the pcv hose behind the throttle body and slightly below it on the drivers side of the engine. i did a v-6 lincoln once that was a $2 part to fix, but i had to remove both intake manifolds to fix it.

that all being said......get a new hose, and get that pcv back on ASAP.



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