SES light came on....00 T/A
SES light came on....00 T/A 
Teching In
Joined: Mar 2004
Posts: 48
Likes: 0
From: Fort Lewis, WA 98433
Originally Posted by seadoo
gave this code...... P0420 catilyst efficiency below threshold ( Bank 1 ) .... WTF does that mean.......HELP ME !!! 
Means of a few repair:
-Fuel Injectors need to be clean.
-MAF in going inop (if that where true both banks would say Catilyst efficiency below Threshold bank 1 & 2.)
-Need new Spark plugs.
-maybe but doubtful poor gas.
-Mastronardi
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 960
Likes: 1
From: Central, FL
well isnt that just freaking wonderful....how do i fix that?
nm, so a good set of plugs, wires, and some injector cleaner would help?
nm, so a good set of plugs, wires, and some injector cleaner would help?
Originally Posted by Mastronardi
Catilyst efficiency below Threshold (bank 1) means the either the left or right side of your motor (injectors)(I can't remember which side is bank 1) is either running to rich or to lean (I think it is rich) which is causeing your CAT to brake down.
Means of a few repair:
-Fuel Injectors need to be clean.
-MAF in going inop (if that where true both banks would say Catilyst efficiency below Threshold bank 1 & 2.)
-Need new Spark plugs.
-maybe but doubtful poor gas.
-Mastronardi
Means of a few repair:
-Fuel Injectors need to be clean.
-MAF in going inop (if that where true both banks would say Catilyst efficiency below Threshold bank 1 & 2.)
-Need new Spark plugs.
-maybe but doubtful poor gas.
-Mastronardi
Bank1 (or bankA) being that side of the motor with pistons 1,3,5,7 and bank2 being the side with pistons 2,4,6,8.
Now I am no diagnostic expert, however, I am not running catalytic convertors (cats) and I get P0420 and P0430 all the time. Prior to removing the cats, I did not get these codes. I assumed these are going off because the rear O2's are picking up excess unburnt fuel, thus 'thinking' that the cats are not working effeciently, or at least below the required effeciency. They are effeciently taking up space in the garage....muhahahahaha.
P0171 Oxygen Sensor System Too Lean Fault Bank A
P0172 Oxygen Sensor System Too Rich Fault Bank A
P0174 Oxygen Sensor System Too Lean Fault Bank B
P0175 Oxygen Sensor System Too Rich Fault Bank B
I thought the above codes were the ones which indicated a too rich/lean condition as sensed by the forward O2 sensors (the O2 sensors upstream of the cats).
Please correct me if I'm wrong on this....
I would call a dealer and ask them what the code means to them. Maybe it's just the cat needs to be replaced. It can't hurt to run some injector cleaner anyway.
Now I am no diagnostic expert, however, I am not running catalytic convertors (cats) and I get P0420 and P0430 all the time. Prior to removing the cats, I did not get these codes. I assumed these are going off because the rear O2's are picking up excess unburnt fuel, thus 'thinking' that the cats are not working effeciently, or at least below the required effeciency. They are effeciently taking up space in the garage....muhahahahaha.
P0171 Oxygen Sensor System Too Lean Fault Bank A
P0172 Oxygen Sensor System Too Rich Fault Bank A
P0174 Oxygen Sensor System Too Lean Fault Bank B
P0175 Oxygen Sensor System Too Rich Fault Bank B
I thought the above codes were the ones which indicated a too rich/lean condition as sensed by the forward O2 sensors (the O2 sensors upstream of the cats).
Please correct me if I'm wrong on this....
I would call a dealer and ask them what the code means to them. Maybe it's just the cat needs to be replaced. It can't hurt to run some injector cleaner anyway.
Last edited by Proud2bSS; Apr 5, 2004 at 10:01 PM.
Teching In
Joined: Mar 2004
Posts: 48
Likes: 0
From: Fort Lewis, WA 98433
Originally Posted by Proud2bSS
Bank1 (or bankA) being that side of the motor with pistons 1,3,5,7 and bank2 being the side with pistons 2,4,6,8.
Now I am no diagnostic expert, however, I am not running catalytic convertors (cats) and I get P0420 and P0430 all the time. Prior to removing the cats, I did not get these codes. I assumed these are going off because the rear O2's are picking up excess unburnt fuel, thus 'thinking' that the cats are not working effeciently, or at least below the required effeciency. They are effeciently taking up space in the garage....muhahahahaha.
P0171 Oxygen Sensor System Too Lean Fault Bank A
P0172 Oxygen Sensor System Too Rich Fault Bank A
P0174 Oxygen Sensor System Too Lean Fault Bank B
P0175 Oxygen Sensor System Too Rich Fault Bank B
I thought the above codes were the ones which indicated a too rich/lean condition as sensed by the forward O2 sensors (the O2 sensors upstream of the cats).
Please correct me if I'm wrong on this....
I would call a dealer and ask them what the code means to them. Maybe it's just the cat needs to be replaced. It can't hurt to run some injector cleaner anyway.
Now I am no diagnostic expert, however, I am not running catalytic convertors (cats) and I get P0420 and P0430 all the time. Prior to removing the cats, I did not get these codes. I assumed these are going off because the rear O2's are picking up excess unburnt fuel, thus 'thinking' that the cats are not working effeciently, or at least below the required effeciency. They are effeciently taking up space in the garage....muhahahahaha.
P0171 Oxygen Sensor System Too Lean Fault Bank A
P0172 Oxygen Sensor System Too Rich Fault Bank A
P0174 Oxygen Sensor System Too Lean Fault Bank B
P0175 Oxygen Sensor System Too Rich Fault Bank B
I thought the above codes were the ones which indicated a too rich/lean condition as sensed by the forward O2 sensors (the O2 sensors upstream of the cats).
Please correct me if I'm wrong on this....
I would call a dealer and ask them what the code means to them. Maybe it's just the cat needs to be replaced. It can't hurt to run some injector cleaner anyway.
Mastronardi
Just found this in another thread in this forum using the search tool:
DTC P0420 or P0430
Circuit Description
In order to maintain reasonably low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls 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 the NOx to nitrogen. The powertrain control module (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.
Basically, I think the dealer (or OBDII capable shop) has to test to determine if it 1) all the connections and the O2s are working okay, then 2) check the cat.
If it is the cat, and you are mostly stock (or can get there easily) the manufacturer has to warranty the cats for at least 50,000 miles (or maybe the 8/80,000). But I would check some other things first, then make sure they don't try to get you to pay anything for the cat going bad.
Found this also:
I am a GM technician and in my experiences the P0420 code for catalyst low efficiecy has always resulted in a malfuctioning converter. This is the only reason this code will set. If the sensors aren't functioning properly, there are several other codes that will set for them. You need a new cat.
and this:
That IS a code for a bad cat, but it could just as easily be a bad O2 sensor. The way to find out is to switch your O2 sensors. If you throw P0420 it's the sensor, if not, it's the cat.
Try this and tell us what results you get. Could save you a bunch of $ from a shop/dealer. O2s can go bad also....
DTC P0420 or P0430
Circuit Description
In order to maintain reasonably low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls 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 the NOx to nitrogen. The powertrain control module (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.
Basically, I think the dealer (or OBDII capable shop) has to test to determine if it 1) all the connections and the O2s are working okay, then 2) check the cat.
If it is the cat, and you are mostly stock (or can get there easily) the manufacturer has to warranty the cats for at least 50,000 miles (or maybe the 8/80,000). But I would check some other things first, then make sure they don't try to get you to pay anything for the cat going bad.
Found this also:
I am a GM technician and in my experiences the P0420 code for catalyst low efficiecy has always resulted in a malfuctioning converter. This is the only reason this code will set. If the sensors aren't functioning properly, there are several other codes that will set for them. You need a new cat.
and this:
That IS a code for a bad cat, but it could just as easily be a bad O2 sensor. The way to find out is to switch your O2 sensors. If you throw P0420 it's the sensor, if not, it's the cat.
Try this and tell us what results you get. Could save you a bunch of $ from a shop/dealer. O2s can go bad also....
Last edited by Proud2bSS; Apr 5, 2004 at 10:37 PM.
