I'm really concerned cause I try to go to extra measures to keep the "quality" of my car up. I have everything installed by an exhaust shop I trust (my only install was the b&m). This light came on while sitting at a red light. Car still seems to run normal with no weird noises. Any ideas on what the CEL is and should I let my dealer charge me 37.50 just to find out what caused it????

go to autozone.....get it scanned


Can't find out what's wrong when you dn't know that the PCM is sayin.


Unless you still have warranty, then go to the dealership.......

Or you can go to fucking advanced auto parts or autozone and have it scanned for free.

Psst, relax it is just a CEL....:lol:


Probably p0171(lean on bank one) or p0172(rich on bank one)

this is a common misconception, many people think that just because they get a cel their car is going to blow up, or stop working or something. step one is to get teh code scanned. could be anything, from something stupid like a loose gas cap, or a code from the exhaust or something. a loud fart will even sometimes triggger a code in a cobalt. if the car is driving fine, and nothing has changed in the way it works, there's most likely nothing to worry about. but no one can help without the code.

my engine comes on and off all the time im assuming has something to do with the exhaust

my engine comes on and off all the time im assuming has something to do with the exhaust

my engine comes on and off all the time too.....just depends what position the key is in
:-P lol

yea it sucks i hate it when it comes on runs lousy man i need some engine mounts i floor it so i can make the light and all i get is "low traction wheel hop" like crazy

welcome to the CEL club?

Where is the plug to scan my car? Autozone couldn't find the plug.

Where is the plug to scan my car? Autozone couldn't find the plug.

then they're retards. it's in the same spot it is in in pretty much every other car since the 90's. below and to the left of the steering wheel is the plug.

Dont mean to thread-jack at all,

first cel isnt really something to write about imo.

first limp-mode is. Week ago i got my first limp mode for running my car around 105-115 for about 25 minutes. I could have kept driving it but decided to pull it over. I did notice that my RPMs went to 0 driving it to the next exit. Dunno if that is what caused it or if it is in limp mode that the tach just turns off.

Either way I turned it off, turned it back on and raced it the rest of the way without an issue. The cel also turned off, kinda weird.

btw limp mode feels like your driving a 90 hp engine with a boost guage doing nothing for you.

Ok , I got it scanned

Code P0420

Definition[B]
Catalyst efficiency low-bank 1

[B]Explanation
The oxygen sensors monitor the catalytic converters ability to store oxygen

Probable Causes
1. Catalytic Converter defective (failure possibly due to #2, 3, or 4)
2. Engine misfire or running condition
3. Large Vacuum leak
4. Engine oil leakage into exhaust-valve guide seals, piston rings



Holy shit I hope this is a complicated way of saying I need to tune for all my exhaust. Let me say that my car still seems to run fine. No weird noises or different operating conditions. Could it be spark plugs??? I have colder plugs, just not installed yet. Is this code normal for people who install high flow cats???? I'm so clueless....what should I do?

Ok , I got it scanned

Code P0420

Definition[B]
Catalyst efficiency low-bank 1

[B]Explanation
The oxygen sensors monitor the catalytic converters ability to store oxygen

Probable Causes
1. Catalytic Converter defective (failure possibly due to #2, 3, or 4)
2. Engine misfire or running condition
3. Large Vacuum leak
4. Engine oil leakage into exhaust-valve guide seals, piston rings



Holy shit I hope this is a complicated way of saying I need to tune for all my exhaust. Let me say that my car still seems to run fine. No weird noises or different operating conditions. Could it be spark plugs??? I have colder plugs, just not installed yet. Is this code normal for people who install high flow cats???? I'm so clueless....what should I do?

If you are under warranty get the cat replaced under warranty.

And calm the fuck down it is a stupid little light.

46,000 miles (out of warranty), and they won't like my full exhaust which is mainly zzp product. No chance of replacement. ZZP would want proof before they replace my dp.....just like they would want proof that my whisper resonator rattles :cussing:

well, emissions equipment (cat) has an 8 year 80k mile warranty FYI


But your code means the efficency is below the factory specs.....nothing wrong with it, common problem with an aftermarket cat.......can have it turned off with HPT

46,000 miles (out of warranty), and they won't like my full exhaust which is mainly zzp product. No chance of replacement. ZZP would want proof before they replace my dp.....just like they would want proof that my whisper resonator rattles :cussing:

Get a catless one and have whoever tunes you turn off p0420

Take off the resonator and shake it by hand...if it rattles then make a vid.

Simple as that.

Ok , I got it scanned

Code P0420

Definition[B]
Catalyst efficiency low-bank 1

[B]Explanation
The oxygen sensors monitor the catalytic converters ability to store oxygen

Probable Causes
1. Catalytic Converter defective (failure possibly due to #2, 3, or 4)
2. Engine misfire or running condition
3. Large Vacuum leak
4. Engine oil leakage into exhaust-valve guide seals, piston rings



Holy shit I hope this is a complicated way of saying I need to tune for all my exhaust. Let me say that my car still seems to run fine. No weird noises or different operating conditions. Could it be spark plugs??? I have colder plugs, just not installed yet. Is this code normal for people who install high flow cats???? I'm so clueless....what should I do?


I got the same code when driving from cali to arizona and i have the exact same ZZP setup. From my research it not a big deal but a custom tune normally fixes the issue or as other said remove it with HPT. I reset the code when i left AZ and have yet to see it again (~400 miles after the reset) with highway driving for hours on end.

-Brad