pinoy131

aight i just got back from autozone with the codes. P0420 and P0430.

PREVIOUS POST: i got a check engine light recently, so i took it my ford dealer to find out what it is and they say that they are my sensors on my exhaust and that it is bc of my aftermarket mid pipe. but heres the deal. i installed my bassani catted x pipe awhile ago, in the summer. all summer and throughout fall and part of winter, my check engine light never came on. how come all of a sudden im getting that check engine light. its just a solid check engine light, not flashing. and all i have is a k&n and flowmaster 40's mufflers WHICH i will change for noice catback set up. any thoughts why this is happening? thanks

owero01

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.

Basically this means that the oxygen sensor downstream of the catalytic converter on bank 2 is detecting that the converter is not working as efficiently as it should be (according to specs).

charliebrown266

i agree with the above post,the rear o2 sensor are there to see if the cats are working efficiently ,and may fine tune air/fuel mixture.

desslok40

I got the same light when I had LT headers and X pipe installed, you may want to check on the cats themselves, I have already gone through one set of SLPs, the ceramic substrate inside breaks down and by the time I checked the whole thing
was hollow!!! lol

I also just had Brenspeed disable the DTC for "O2 sensor slow resp." on my tune, so I don't get the annoying light, the light may cause an issue with emissions testing but I have until 2011 here in AZ, I kept my stock exhaust manifolds and H-pipe just in case.