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Getting a 0420 code. Points to a problem with level 1 catalytic converter. Car runs perfect, no sulfur smell. Test code, engine light comes back on a day or 2 later. Have read about catalytic converter cleaners Any body had success with them? Also, why are some converters around 250 and some around 1250? They both are an exact fit.
A P0420 can also be caused by an exhaust leak downstream of the front O2 sensor to upstream of the rear sensor so it’s not always a bad cat…don’t know what state you live in but CARB (California Air Resource Board) certified cats are way more expensive than non CARB certified !!
You should get someone with a scanner to observe the front and rear O2 sensor signal.
Below is a view when I checked the cat respons on my car (2000) last year.
If the cat is gone it has no capacity to store O2
First I verified my O2 sensors like this :
First I disconnected my brake booster hose and observed the O2 voltage drop to less than 0.1 volt .
Secondly I injected propane in the intake and observed all my O2's go rich (above 0.9 volt)
Then I shut of the propane and observed the delay between the front and rear O2's goes lean .
If both front and rear O2 sensor signals drops without a delay there is no O2 storage capasity left in the cat(s)
Mine had a delay of approx 5 sec .
If the cat(s) is gone the front and rear O2 signals will both have behavour (swing between 0.1-0.9 volt (approx)
My rear sensors stabilize on 0.7-0.8 volt due to my cats are OK.
You should get someone with a scanner to observe the front and rear O2 sensor signal.
Below is a view when I checked the cat respons on my car (2000) last year.
If the cat is gone it has no capacity to store O2
First I verified my O2 sensors like this :
First I disconnected my brake booster hose and observed the O2 voltage drop to less than 0.1 volt .
Secondly I injected propane in the intake and observed all my O2's go rich (above 0.9 volt)
Then I shut of the propane and observed the delay between the front and rear O2's goes lean .
If both front and rear O2 sensor signals drops without a delay there is no O2 storage capasity left in the cat(s)
Mine had a delay of approx 5 sec .
If the cat(s) is gone the front and rear O2 signals will both have behavour (swing between 0.1-0.9 volt (approx)
My rear sensors stabilize on 0.7-0.8 volt due to my cats are OK.
0420 code
