Gas Cap Loose Message Then My Engine Light Came On

Nick2000Gmc · February 19, 2009

Hey everyone I am the new ( to me ) owner of a 2007 (classic) Silverado, and I am having a problem. I was driving and hit a bump on the highway and then my dic said that the gas cap was loose. I stopped and tightened the cap and everything was fine till a couple days later. I had the same message again and I tightened it and cleaned around the cap. Then when I started the truck back up it has an engine symbol on the dash that is not flashing but just steady. Anyone know if there is a common problem I should try first and also would the engine light be caused by this or could this be something else. I appreciate all the help.

chrisbmo2000 · February 19, 2009

Yes the CEL is because of the loose gas cap......sounds like you may need to buy a new one if it keeps coming loose

Z45 · February 19, 2009

You are tightening the cap till it ratchets correct? Don't get mad, I know someone who thought they broke the cap when they heard the ratcheting sound.

I had this happen on my 2005 CTS just after fueling and OnStar said it could take up to 5 starts before the warning clears. Turned out the gas cap was not the reason for the check engine symbol, defect cats was.

masonbid · February 19, 2009

I had the "tighten gas cap" message appeared. I filled up with gas and when I started my truck, the CEL came on. It lasted about 4 days until it shut itself off even after retightening the cap several times.

The work silverado has the CEL come on but no loose gas cap message. Tightened the cap and it disappeared...

Hope it works out for you in the end!

BlackOut V8 · February 20, 2009

This problem occurrd after I purchased a locking gas cap. The gas tank and system is pressurized and if the gas cap is loose or the O-ring seal is wrecked the CEL will come on. As soon as the system is at correct pressure the light will go off. The light goes on to prevent any leaks into the atmosphere. Check your rubber o- ring seal around the cap and if it is twisted you can lube it. Hope this info helped.

Thanks,

BlackOut V8

dorman68 · February 20, 2009

Sounds like you might have a small leak somewhere in your evap system.

Zembonez · February 20, 2009

Sounds like you might have a small leak somewhere in your evap system.

True. It might not be the cap causing the error. If cleaning the lip and cap and making sure it is tight doesn't solve it, I'd look into another air leak in the filler neck or the evap system.

mr_bots · February 20, 2009

Sounds like you might have a small leak somewhere in your evap system.

+1 I got that message in my old car, turns out the evap purge solenoid was broke off by the dealer when they replaced a misdiagnosed transmission shift cable. Although it is usually the gas cap, and they do sometimes go bad. You could also always just unplug the battery for 10 minutes to reset the code.

Nick2000Gmc · February 24, 2009

Update

I had the truck at the dealer today and they checked the computer and it just required a re program ( apparently needed to relearn or something ) anyways all is good