[DonnieAzoff1]

I have a 17 Sti with a stage 1 cold air intake, and GFB hybrid blow off valve. tuned with Cobb and a borla catback exhaust. I keep getting the same code everybody else gets but clearing the code makes my car drive annoying while it relearns. Anyone have recommendations on how to solve the issue?

 

[405HP_Z06]

Do you have an aftermarket downpipe?

 

[DonnieAzoff1]

Do you have an aftermarket downpipe?

I don’t believe so, I bought the car used and never had an issue with the code until I switched out the intake and added the tune in. Is it possibly a bad cat converter?

 

[405HP_Z06]

Could be a convertor or rear oxygen sensor.

 

[DonnieAzoff1]

Could be a convertor or rear oxygen sensor.

Possibly dumb question, besides the CEL coming on and messing up cruise control, any damage being done if I don’t fix the issue for now?

 

[405HP_Z06]

That is a tough question to safely answer. If the code is tripping due to a sensor, it would be acceptable to allow more time before repair. If the code is tripping due to a convertor, then you may want to address the issue sooner rather than later. Sometimes you get a code that is a sign of a bigger issue at play.

 

[PhoSho]

I would wager that the P0420 code was disabled in the rom due to a downpipe or bad CAT and when you flashed that Cobb Stage 1 map, the code was re-enabled and tripped. Stage 1 and 1+ Cobb ots tunes never had any codes disabled by default, green speed or otherwise.

 

[Barry]

I had a very friendly dealer replace 2 cats and 2 sensors under warranty. when my RA threw a P0420 code this past summer. Car had about 46K miles on it. Forgot to mention my car is stock.