Just recnetly installed a new header and dp and I am getting a p0420 catalyst efficiency and also now a p1133 code( somthing about air/fuel) Does the p1133 have to do with the new exhaust? I know that the first code really aight that big a deal ( i prolly have a leak ) but is the air/ fuel code sumtin to worry about or is it just coming up in relation to the p0420 code. I never had a CEL before the install. The car seems to be running fine. Any input would be kool. THX

 

Bump for answer

 

did you disconnect your battery after the installation so the computer could learn? From what i'm reading in the manual it has to do with the o2 sensor bank 1 reading of the rich to lean count which may now be different due to the header change. I'd say unplug your battery for a couple minutes and see if it doesn't turn back on afterwards.

 

1133 has to do with ur o2 sensor

 

every single mod i put on my car,i never unplug the battery and never pop codes...so dont really think the ecu will learn it that way

 

well he doesnt have a header dp combo so i think his cat is taking a **** on him (p0420) and the o2 sensor is malfunctioning with the car being rich

 

many will argue that post-catalytic codes won't cause performance changes, but i've felt somewhat of a difference myself when my CEL's have turned on, i might be with you on the idea that its possibly running a tiny bit more fuel for safety reasons.

Otherwise, i do recommend you unplug your vehicle so it can relearn the changes in your car. A header and downpipe results in a drastic change in air-flow (and ofcourse exhaust flow) and needs compensation from the computer. Some modifications may throw codes, others may not.

Also, from the code that you're throwing, its rich to lean count is showing a difference which is directly affected by the change of length of your primaries of your new header from the stock manifold primary lengths. I always unplug my battery during or after doing any performance modifications.