O.K, I had my ecu updated from A.P.R this week and when i got it back and ran the car, i threw a code p0421 (cat eff below threshold bank 1). the car feels like crap, boost bouncing, peak @19lbs and then drop to 14 or 15. i did a search for the code on the forum butnothing good that can help me fix buy or repair. any help would be great. thanks

 

could be a bad software issue since its just happened after the upgrade take it back and have them check it out

 

o.k thanks, is that common (bad software), also would a vib under the car during start up and cold running be a factor. sounds like a heat shield, cat or clutch.

 

hmmm the heated o2 sensor ( HO2S ) is the item in question as the code states so could it be it was ready to go and the upgrade helped it and screwed the catalytic converter

 

you tell me. lol. i hate to **** money away for new pipes. might try new o2 and call apr about the chip. but then i dont want to put a new o2 and have the same prob if the chip or cat is bad....