Question about 2003 Chevrolet Impala
2003 chevy impala 3.8 engine. Hard starts 50% of times and smells of fumes when this happens. I have a code of P0420. Had the Cat converter changed 2 years ago. The 02 sensor was NOT changed then. Car now has 145K on it. Could this be my 02 sensor? Thx
This is what i found for you
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensorwaveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.
Most likely, the aftermarket cat they installed is a high flow cat. This commonly causes issues with throwing that code on our cars. You can either have an OE cat installed, or just have the code deleted from the PCM by someone that has a tuner.
Posted on Jan 10, 2013
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Posted on Jan 02, 2017
I can't answer the question about the gas fumes, but I had the same problem last year with the "Service Traction Sysytem" message and the Trac and ABS lights coming on in my Impala. Mine turned out to be because of a bad wheel bearing, that was causing the ABS and traction system not to work. I'm not sure if you've experienced this, but another thing that would happen with mine was that I would go to brake and have a hard time depressing the brake pedal, almost like it was pushing back. That is the point when the Trac and ABS lights came on.
Posted on Jan 22, 2009
I think you will find the aftermarket Cat Conv. is the source of your problem, but without hooking up to the factory test equipment at my disposal at my Ford dealer this at best and educated guess based on 20 years of emission related work, I am a Ford certified master electronics technician
Posted on Jan 30, 2009
from what i am finding the code means o2 sensors. they recommend replacing them and if this does not work than replacing the cat converter
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.
A code P0420 may mean that one or more of the following has happened:
Some suggested steps for troubleshooting a P0420 code include:
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Posted on Aug 20, 2009
Try under the dash, attached to colum is a switch that the rod goes into from your ignition key switch, that may need to be adjusted tword your steering wheel just a touch, they go out of alignmnet from time to time
Posted on Sep 15, 2009
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