Tundra 03 My engine light went on yesterday. I changed my gas cap to a locking cap the week before. Went to Autozone they checked the sytem out for free. It was the locking gas cap that caused the problem. They reset the sytem for me. Check engine light out. Thanks to this group for the heads up and Autozone.
Check Engine Light gas cap!
Jan 18, 2006
1 Replies
They gave you the wrong locking cap. There is a calibrated relief valve in newer caps meant for emissions controlled cars, and a simple vent breather hole in the caps for older cars.
On emissions cars the relief valve in the cap has to hold up to a certain pressure and/or a certain vacuum in the fuel tank before it vents either way, because the emissions system wants to keep the tank at a slight vacuum when running - if there's a leak that keeps the vacuum from developing, it trips the 'Check Engine' Light.
-->--
Join the Discussion
Have something to add? Share your thoughts — no account required.
Didn't find your answer?
Ask the community — no account required