Most remove catylic converter simply to get more exhaust flow through the exhaust. If you do this a PO420 code pops up. What will this code do to a car? Run in open loop and never be in closed? Does effect short and long term fuel trims, make run richer? Or is this just simply to let you know the cat isn't working properly and does nothing except just a cel? I've tried searching and can't find a REAL answer. Is this the same for all computers in cars or do they vary?

just tells you that you need a new cat....... its called an idiot light


01' Z24 5 speed
422whp/400wtq
T4 Turbocharged
Built LD9
HP Tuners

Ya, it's telling you there's no cat basically. I'm not sure how your fuel trim will be affected though.

I've seen some cars not even give a @!#$.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

Yup, just there to make you pass emissions, shut it off with hptuners or put a spark plug defouler to space the o2 sensor back (only the back one) and call it a day.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Fuel trim isn't affected at all.

I know a lot of people that wired resistors into their vref circuits back there to satisfy the PCM. Therefore no CEL!

Mines been on for over 8 years lol.