Code P0420

[JimH]

I just joined the forum today. So, I'm sure this has been discussed but can someone please give me some help??

My 2000 Tahoe with 5.3 engine is running rough at idle, sometimes dies. The code scanned was P0420 and the print out gave me several possibilities. The codes were reset two weeks ago and the car ran OK until two days ago, and gave the same codes again. Out of the possibilities, should I just go ahead and change the bank 1 O2 sensors or what do you suggest.

The car has about 135,000 miles and I know all the sensors are original. I am second owner.

Any help would sure be appreciated.

Jim

 

[samotahoe]

take out one bank o2 sensor at a time. and make sure its the upstream. if it runs better with a particular sensor out then that side catalytic converter is clogged

 

[rockenthebowtie]

I agree with samotahoe.. just incase samotahoe is to technical for you upstream means the 02 sensor between exhaust manifold and the catalytic converter

 

[JimH]

So I take one "upstream" sensor out at a time, but do you just leave the hole open or do you have to find a plug to put in it? I also thought about moving both left side sensors to the right side and see if I get 0430. I think that code is the same faults, but on right side bank.

I have been given info that if it is one of the sensors it almost always is the rear ones not the front. But, I realize you will get a lot of info on your car problems. Some of the info is good some not. I have a mechanic buddy that says it could also been that the throttle body is filthy and causing a mixture problem. Wow, I've got to try something. It sure is funny to me that the car ran fine after the codes were reset for a week and a half. Then the faults came back and so did the lousy running car.

If the idea is to take one possible sensor out of the loop at a time, couldn't you just unplug the sensor at the harness. Then start the car and see how it runs?

Jim

 

[rockenthebowtie]

Yea your right about P0420 being bank 1.. remove that 02 sensor leave the hole open and run the the truck yes its going to be loud but if the cat is plugged the exhaust will escape from the 02 sensor hole and see if it runs better aside from the loud exhaust noise

 

[samotahoe]

^ what he said:happy160: