I am new to this so I hope I am doing this correctly.
I have recently purchased a 01 Blazer LT. I took my Blazer in yesterday to get it serviced in order to keep the extended warrenty we purchased in good standing. After picking up the Blazer I noticed the check eng. soon light was on and would not go off. We have driven it 3000 plus with no lights, no problems until now. I contacted the business where we had it serviced and purchased from and they are trying to blame the light on something else.(Go figure...extended warrenty!) When I opened the hood I discovered the filler cap was off. With all the sensors this thing has would this not light one up? Also when the engine is first started after a oil change it will have no oil pressure for a moment, won't this set the sensor off as well? What I need to know if anyone can help is how do you reset this if you were doing your own oil changes, which I will be doing after the warrenty expires. I would like to try reseting myself before paying them to rob me. I have disconnected the Neg. and also the Pos. on the battery for 5 minutes and reconnected, I was told to try this but the light still remains on. Please help me if you can and would. I have worked on and rebuilt many eng. in my time but this new electronic crap has got me stumped.HELP!!!!!! Thank you

 

Nope.
Nope, that's normal until the pressure builds.

You need to stop by AutoZone, have them read the SES code, and report back in this thread with the result.

 

where r you from? i have a scanner.

 

G_Mike,
Thanks for the reply, apparently it takes a few, like 3 hours for the computer to do a re-scan on the system. The wife took the rig to town today and before she got home the check engine soon light had cleared itself. Must have been the cap being left off of the filler spout that caused the light to come on to begin with.
Thanks again.... by the way, I am from Spokane, Wa.

 

Yeah, sometimes it takes so many key cycles. Glad you found the problem though, you might put your location in your profile information for future reference.

 

For the light to go off does not require 'key cycles', but rather 1-5 'drive cycles'. Once again, 'no', the oil filler cap being left off had nothing to do with the light coming on. There is no sensor involved with the cap. Replacing it and the light going off were coincidences. It was driving the vehicle and allowing it complete the 'drive cycle', thereby letting the OBD II system check itself, that turned off the light. If my earlier recommendation of having the code read while the light was on had been followed, we would have more info.