I know this is usually expected. I installed my longtubes/Y-pipe a week ago....then new cat-back 2 days ago. The engine light came on this morning. This is a 2002 Silverado with 5.3.

So I stop by Autozone because I just want to make sure that a P0420 is the only code to show up...since the cats are gone now. Well, he said there were 8 codes. Then he corrected himself and NO, there's the same code 7 times, then the P0420 code which I expected. The code that popped up 7 times was P1154 (heated oxygen sensor - bank 2, sensor 1, transition time ratio). Why would this show up 7 times? Could it be recorded in the history making it show up that many times? I never had the light come on before now and I've had the truck for 4 years and 40K miles. It has 134K miles on it.

The bank 2 sensor 1 is located after the collector on the Y-pipe. That collector did not seal 100% for the 1st week, but no light. When we installed the new pipe, muffler and tail pipes, we took the extra time to tighten that collector so that it did seal 100%. So a day and a half later AFTER we seal the collector leak, the light comes on. I'm wondering, could the collector not sealing cause the sensor to trip the light? OR, could welding on the exhaust shorted out that sensor? OR, could it just be coincidence that the sensor happened to go bad during all the bolt-ons?

Ever since the headers were installed, I have noticed that 'burning rich' odor from the exhaust. I figured it was probably some oily residue inside the new pipes or whatever that was burning off. I'm thinking it has to do with the collector on that side not sealing up causing it to run a little fat on that side. Am I off base with my assumption?

But lets say I did get the collectors to seal after the light came on. Does the engine light have to be reset manually or will it turn itself off after the readings are satisfied?

 

So I scan the truck again today because I was curious if I had any extra codes. I also had a theory about clearing any/all codes to see how long before the light comes back on. To my surprise, the P1154 code is gone. I wonder if it has to do with getting a more complete seal on the collector on that side.

Now all I get is P0420 and P0430....due to the converters being deleted. I cleared the codes to I won't have to stare at the light for a few days. I'll drive it as is to see how long it takes for the light to come on and I'll scan it again. Trying to get an appointment with the tuner to have the rear sensors disabled.

 

Did you ever get this figured out? If so, how? I'm having similar issues after my header install.