I have a granetelli(sp?) mass air tuned to go with a k&n filter and it causes the 'check engine' light to come on. How are you able to turn the light off? I just bought the truck from the original owner and he gave me this with the truck and told me that is what happens when it is installed. Thanks in advance.

 

Two choices:

1. Remove it.
2. Get a proper custom tune for it.

You can clear the light with a scan tool, but it will likely come back on if that MAF is causing a lean condition.

 

x2

you're gonna damage your engine if it's not already.

 

It is not on the truck. The guy I bought the truck from originally ordered it and put it on and the 'check engine' light came on so he took it off and put in back in the box. I probably won't try to put it on there unless I get it tuned. Thanks for the info.