Hey guys. I was driving today, and my SES light came on. I also noticed that my water temp was lower than usual, which was odd since it's like 85 today, and I was in traffic (BTW, I have a Hypertech 160 -t-stat). I went to the Chevy dealer, and popped my hood while the engine was running, and the cooling fans were on. I talked to a tech, and he said to check the ECM Water Temp Sensor. The parts guy showed me a picture, and it threads into the water pump. I went back to my car and tried to scan the codes with my Auto Zone code key (which never has worked on my car, which is another question I have. Why doesn't it work?) I started the car, and drove awhile, and the temps were normal and the SES light never came back on. Any ideas?

 

Well I couldn't tell you without scanning what exactly is causing your SES, but as far as the AutoZone code key, if it is what I'm thinking (paperclip or something more fancy looking but doing the same thing) then this will only work on the 93 LT1 and not on the later years.