A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Chevrolet Trailblazer SS Check Engine Light Due to Gas Cap Issue
Chevrolet Trailblazer SS Problem
Average Mileage: 80,100 mi (66,500 mi - 101,200 mi)
Visitor, 2006 Chevrolet Trailblazer SS, 66,500 mi
Check engine light on steady. Also received the "tighten gas cap" message. Will replace cap with new and report back if that doesn't fix it. 7/17/14
Visitor, 2006 Chevrolet Trailblazer SS, 101,200 mi
tighten gas cap light still on . bought new oem gm cap and that fixed the problem for awhile now its doing it again .
Visitor, 2007 Chevrolet Trailblazer SS, 69,700 mi
Filled gas tank, started truck, fuel light came on, fuel needle went to empty and CEL came on.
Visitor, 2006 Chevrolet Trailblazer SS
bought a new gas cap but it still getting tighten gas cap