Illumination of the Check Engine Light can be caused by a loose or worn gas cap.Google+
Car Problem Reports
Chevrolet Blazer Check Engine Light Due to Gas Cap Issue
Chevrolet Blazer Problem
Average Mileage: 93,428 mi (13,000 mi - 182,000 mi)
check engine comes on but wont go off
Visitor, 1997 Chevrolet Blazer
Check engine light came on. I had Autozone check the reading and it showed the gas cap needed replacing. I replaced the gas cap twice and still the same problem.
have owned my blazer since 2003 and have replaced the gas cap 3 times.
Visitor, 2002 Chevrolet Blazer, 13,000 mi
Same exact problem the mechanic just turns off the code now,.
My service engine soon light came on so I took it to the Chevy dealer. They checked everything out and said the engine was fine but I probably over-tightened the gas cap and that set off the engine light.
Not a huge deal but rather inconvenient and sometimes costly because you have to pay a mechanic to check it out just to make sure its not something more serious.
evap emmisions leak(small leak detected) so i replaced the cap,cleared the code and it never came back.
Check engine light came off, mechanic check this issue with his computer thingamagig and it was reading something to do with my sensors. He didn't do work on those because I just had an engine installed so they are suppose to be new. Then he turned my gas cap and light went out. It has come on again and so far I haven't done anything about it but am going to soon. He has got to recheck the engine and all components before I will be satisfied that it has nothing to do with the work he did.