Check Engine Light Due to Gas Cap Issue on Chevrolet Silverado 2500 HD

Illumination of the Check Engine Light can be caused by a loose or worn gas cap.

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Average mileage: 95,601 (43,000–178,000)
Exhaust & Emissions affected: Gasoline
7 model years affected: 2001, 2002, 2003, 2004, more2005, 2006, 2007
20 people reported this problem
7 people shared problem details
CHECK ENGINE LIGHT COMES ON THE IT SAYS TIGHTEN FUEL CAP ON THE DASH
Frustrated. I have a 2500HD 6.0 with 173,000 mile. Never a problem until now. The check engine light came on, so I had it diagnosed and the code said bad fuel cap. I also informed the mechanic that I don’t have any very little power at take-off. The mechanic said it could also be the catalytic converters are plugging up. I replaced the catalytic converters, which seemed to change the power issue. However, I still have the engine light stating a bad fuel cap. WTF. I removed the fuel cap and the truck starts and runs normal. However, now, when I fuel up the truck, it doesn’t want to start and it takes several cranks to start, and then it sounds flooded. I don’t know where to start. The truck runs fine until I fuel it up, and then it takes several attempts to start the engine.
Check engine came on when engine was started . Did code check... it said evap problem . Gas cap o ring showed light wear . Installed new cap and cleared code ... check engine light off on restart.
Come to find out after a smoke test the electric fuel pump return Line had s crack causing air to leak. Tripping the engine code light. This is a common issue with trucks. Solved my sluggish power also
runs good filled it up with diesel and noticed later check engine light came on
Still not fixed have been through three gas caps and a dealership code check, going to Napa to get top of the line fuel cap have heard rumor this will help?
gas cap turns engine light on...
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A loose or worn gas cap could be cause the Check Engine Light to illuminate.

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