My 95 z28 check engine light keeps going on and off, I noticed that my fans kick off the light goes off. Does any one have any clue what might be going wrong??? I'm also getting a lot of oil slim up around the throttle body, so I think it might be the EGR valve but i'm not sure what it could be. That is my first question. The low colant light also is on, I checked it and that colant is fine, is the sensor bad and how hard is it to replace???

 

The low coolant sensor commonly fails and is easy to replace. It's located right below the fill neck of the radiator and is easily accessed by removing the battery. You'll need to drain about half the radiator so as not to spill fluid when you pull out the old sensor. Shoebox has a photo of the sensor:

http://shbox.com/1/low_coolant.jpg

As far as the Check engine light, you need to have the PCM scanned to determine the code; the PCM will store codes if the light happens to be off when it's scanned.

 

I have had the same exact problem with the engine light/fans. They will run in the dead of winter. Mine would only cut off if at a stop in gear(automatic). As soon as they cut off, the SES light goes out. I scanned and found that my egr connector was unplugged and capped. No idea how it happened because the only time a mechanic has had my car was for the AIR PUMP recall. After plugging that in, fixed the SES light/fan issue but then the fans would never come on and I would overheat. 3 new relays, no fix. So I basically had to disconnect the coolant temp sensor and let the fans run all the time over the summer.

Engine/tranny is now out of the car. Tranny is rebuilt and will be starting the engine soon.
BTW, never did solve the problem but there have been a few people with this issue and yet to see a cause. I surely hope that when I put the engine back in, while replacing sensors and such, the problem will be solved.

 

The fan comes on because the SES light is on, not the other way around.

 

Doesn't help but thanks. And the ses light does not cause the fans to run, the condition that trips the light is starting the fans if you want to split hairs.