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View Full Version : 2009 Pontiac G8 V6 (LY7) Check Engine Light



boss70
11-22-2012, 04:16 PM
Hey guys I need some help. I bought a v6 G8 and I hate the horsepower of the car and I cant get rid of it bc its all I have (I know I should have bought a V8 but its a long story as to why i didnt) so, needless to say I have been pouring a ton of money on custom parts to be made for the car to make it faster bc V6 performance dont exsist other than a CAI which I also have. Anyway the last thing I have done was I had a custom High flow cat made for my car attached to the orinal bank 1 and 2 O2 cyclinders. After that was done the check engine light has been appearing and been a thorn in my side. The mechanic has no clue how to get rid of it. He said its an odd code he knows what it means but he has never seen it before. We have tried everything under the sun. We filled the resignators hopping that if we slowed and evened the air flow that not so much air would be forced into the old O2 censor making it go away. That didnt work. We thought it may have to do w/ the old O2 censor but replacing it wont do squat. We tried reseting it a few times to see if the car would adapt to the new cat. But now every time we reset it rough estimate of a 100 miles lets say it comes back on. My mechanic looked in a GM guide, we had a G8 guy look at it he didnt know and now I am waiting for this other guy my mechanic knows that specializes in the computer codes on newer cars like this one to see what he knows. Its been over a month and I still have had no word from my mechanic. In the month I have driven it when he hasnt called the "cel" went off for like 3 days and than came back. Idk what the problem is or what I should do I do not remember the code number but I remember it is only on the base 1 side and it says something about the fuel whether its to rich or something. But if anyone knows how to get rid of it I would be forever greatful. I dont want to put the old cat back on and that not solve the problem plus I dont wanna do that regardless bc that would be taking away Horsepower and costing me more $ to take it away. The car will not pass emissions with this nussent code. Thanks guys for any help I recieve.

Crazy Paul
11-22-2012, 04:46 PM
Disconnect negative battery cable, wait 5 minutes, reconnect.
Otherwise give us the exact code number P0(xyz)

-Ray-
11-23-2012, 01:34 AM
Your huge custom high flow cat isn't heating fast enough.

boss70
11-23-2012, 06:23 AM
If you dont mind me asking Ray how would the heating up of the High flow cat fix the problem? I just ask in case my mechanic ask what I mean by it....Thanks.

boss70
11-23-2012, 06:36 AM
HSV-GTS-300 I believe the code # is P0171

-Ray-
11-23-2012, 10:05 AM
If you dont mind me asking Ray how would the heating up of the High flow cat fix the problem? I just ask in case my mechanic ask what I mean by it....Thanks.

The cats need to be hot to be efficient. If they don't heat up within the required time a cat inefficiency code is set.

Crazy Paul
11-23-2012, 01:52 PM
http://www.grrrr8.net/crazypaul/P0171.pdf

WoodburyMan
11-24-2012, 01:42 PM
Hope you figure it out Chris. Maybe just say F it and put the stock cats back on for fun. Keep the rest of the exhaust if you could. I really don't think they would be restrictive in your application. Stock cats should be fine for small HP gains. You'd really only need them if you did a turbo or built the LY7 up A LOT. At least be worth it to try and eliminate the problem.