# Check Engine Light - K&N?



## Nomad (Dec 22, 2009)

Hey,

I have a check engine light that comes on and goes off and I'm wondering if it has anything to do with the aftermarket K&N setup that the previous owner put in. It doesn't have the right gas cap, but I (thought) I got that covered when I got another cap at Kragen. 

The mechanic at the dealer put her on the computer and it came up as running lean. Would the wrong gas cap do that? He reset it and basically accused me of running 87 octane in it. I've been running 91 since I bought the damn thing, so that's not true. This light is driving me nuts. 

Any ideas?


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## jpalamar (Jul 22, 2008)

Go to AutoZone or whatever and get the exhact code. KNN filters if they are over oiled usually cause the MAF to read incorrectly.

Also the gas cap is usually covered by GM. There is a post somehwere on the site tells about the GM gas cap letter and how to get a new one.


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## Nomad (Dec 22, 2009)

Ah. I didn't think about it, but you're right. Auto Zone does read your computer without the huge dealership charge, right? I know each time I take it to the dealer it's something like $125 bucks for them to check it with the computer. 

I called GM and I also went to the dealer about the gas cap. Both sources said I'm out of the warranty period. It expired when my bumper to bumper expired last year. I still have powertrain until next June, but no-go on the gas cap. It's no biggie though. The guys I bought the car from ordered one for me anyway. 

Thanks for the advice!


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## Zrocket (Dec 21, 2009)

Just a thought but have you tried cleaning the MAF?


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## HP11 (Apr 11, 2009)

Nomad said:


> I know each time I take it to the dealer it's something like $125 bucks for them to check it with the computer


Sounds like you need one of these. It would pay for itself the first time you used it. I bought the same one listed for $39.99. 

- Harbor Freight Tools - Quality Tools at the Lowest Prices


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## taz4141 (Nov 6, 2006)

a simple tune would 4 sure work....... regardless , if you bought this car from someone. who knows what was taken off the car b 4 you got it. TUNE IT. then you know...and you'll be happy with the new performance... don't clean the MAF there extremely fragile and if you put a chemical film on them little sniffer wire's or grates ,there done for.if you chose to. I suggest water steaming them. besides if the maf was messed up.the engine would run like sh!t.


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## cky9105 (Dec 13, 2009)

I have the same exact problem i just bought an 05 and a week after i got it i moved my intake because the power steering pully was rubbing and cleaned the filter and after that my check engine light came on and when i took it in a bad fuel/air mix code came back and the service guy said it was running lean the previous owner also put jba headers and the dealer said either could set the light off still trying to fix the problem


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## jpalamar (Jul 22, 2008)

You need to be specific with the code. Not saying it was running lean. What sensor, what code number. ect... Shorties will not cause a CEL and neither will removing a CAI.


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## Nomad (Dec 22, 2009)

Thanks so much for all this info, guys! 

I took her back in to the dealership where I got it, and they cleaned the injectors. They said it was because of "bad gas" that someone had put in. I really don't think that's true, but the check engine light is off and that's fine by me. I don't really know this car yet, but I find it hard to believe the check engine light will come on because someone put a half tank of Arco gas in it. 

My main concern now is that I have no idea what has been done to modify this car. It had a "Smog OK" sticker on the windshield, but after noticing the underside, I'm not sure if it would pass a visual inspection.

Check it:










I'm sure some Nazi will point out to me that I don't have an H pipe at a smog station in a few years and then I'll be on the hook for exhaust work.


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## cky9105 (Dec 13, 2009)

Im not sure of the exact code but on the work order it says they replaced the evap purge solenoid which caused the light to go off but about an hour after driving off the lot the light returned


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