Hello everyone,

Last Wednesday, I had the factory muffler replaced with a Borla exhaust that I picked up for cheap. Been driving it and have noticed a nice improvement in performance and gas mileage. However, yesterday evening I noticed my CEL was on so I ran a scan and it showed the P0420. Could this be a coincidence since I have installed the higher flowing muffler system, or could it be that the Cat is failing as a result of the higher flowing system?

It also has a AirRaid JR CAI on it if that will make any difference in how the system is flowing.

Do I need to get new cats, or would a tune re-calibrate everything to perform correctly. The Burb has 195k miles and I have no clue as to if the cats have ever been changed.

Thanks for any advice you can provide.

 

You likely need a new sensor as with the new exhaust it cannot adjust fuel trim with the old sensors. It happens that the sensors will work within a certain parameter for a long time they have a hard time reading any other levels.
OR


there is a leak

 

I installed all new O2 sensors about 5 months ago. Guess I need to take it to the exhaust shop for them to test it out to determine what the problem is instead of throwing money/parts at it.

 

when you buy a cheap cat, it will have low cerium content. This is the oxygen storing element in the cat. the p0420 will continue to reset. if you have emission testing in your area that uses a gas analyzer; it will fail testing. If you don't have to pass emissions, get the rear 02 programmed out/install a 02 simulator.


I have dealt with this before on a Nissan. p0420 set, customer did not want to spend the money on a oem part and had a muffler shop install an aftermarket cat. code reset so the muffler shop installed another new cat...same problem....oem cat fixed it.

 

Hmm, never thought about getting an O2 simulator. Course, I have been thinking about getting a performance tune. May go that route and have him delete the rear 02 sensors.

Thanks for the information