:confused: Maybe someone has experience with this i hope but about a month after i bought my blazer the service engine light came on and the techs at the dealer convinced me i needed my transmission fluid replaced. Light came on again a week later and their response was it could be one of 80 things. I wasn't gonna pay for them to keep guessing at what was wrong. Here is the scenario of when it comes on the most. Half a tank of gas.........usually going up a hill..........most the times when i top it off again it will go off soon. I tried tightning the gas cap as much as possible. But as late its been on for 2 days now..........help

My 97 blazer did the same thing and I replaced the gas cap about 2 month's ago and the light has not gone on since...so I am hoping that that was the only problem.

the best thing i ever did was go down to discount auto parts and buy a scan tool, so i could read my own codes and determine whats wrong. i spent about 160.00 on it, but i felt it was worth it

The gas cap sounds like it might be the problem, you should check EVAP system, and all the lines for any leaks.