2008 Sierra Check Engine Light

**Drifter** · 05-12-2009, 02:52 PM

I've been having a check engine light come on about once every couple of weeks. I forgot to write the code down and what it said but my question is. Could it be due to the modiifcations I have made to the truck? So far I've added Flowmaster Super 40 catback, Cold Air Intake, Power Aid Throttle Body Spacer and superchips flashpaq tuner. It runs fine still seems to get the same gas milage. I checked the gas cap too, I know this was a problem for some GM products.

**brownpridex111** · 05-12-2009, 04:12 PM

i dont think so i have some mods and o dont have that problem.

**CarpenterGuy** · 05-12-2009, 07:23 PM

I have mods and dont have any problems, but your tuner might have changed something that shouldn't have been. i dont know a whole lot about tuners.

**Drifter** · 05-13-2009, 03:20 PM

I didn't think it should cause a problem and have tried changing to different tunes several times to see if it makes a difference. It didn't so I guess I'll return it to the stock setting an take it to the dealer for them to take a look at.

**Drifter** · 05-27-2009, 06:29 PM

OK guys so the code is P0446 Evap Emission Ctrl System Vent Ctrl Error. No I don't have a lose gas cap. Seems everytime the truck sits for abit the light comes on.