OK, i have a little problem here.... last wensday i did the resitor mod in the AIT (4.7 ohm 1/2 watt) i drove the car for prolly about 1 hour and everything was fine......... i went to start my car friday (been on vacation for a week) and i had been driving for like 2 minutes and my service engine soon light came on. i went back to my house and took out the resitor mod and put it back like normal form the factory and started it up and the light didn't come on..... but after 10 minutes it came on again? what gives? So saturday i had to go to work and when i started my car i noticed that my fan's had kicked on right when i started it.... the car hadn't been driving for 12 hours prior to the start and it is around 30 degree's here in PA. As i was driving for like 2 hours with the service eingine light on, it then shut off while i was still drivng and then went back on withing 20 seconds. I don't have a scanner so i can't scan it . i was thinking it could be a fan relay, or a bad thermostat.... i need some help, here. i am not a pro mechanic, but i like to try and work on my car myself cuz that is the only way i will learn. i have off of school tommorow so i was going to go check it out.......... thanks

 

OH i also forgot to add, that day i when to start it from comming back form vaction my battery was dead, i had to jump it.( dome light was left onso would that have anything to do with it? jsut thought i woudl add that in there............ so basically the light went on after i jumped my car and drove it for about 5 minutes........ and that lound hum noise is the fans corect, i am pretty sure but thought i would just make sure......

 

I don't have anything helpful to add, but I can tell you that the fans automatically come on whenever the SES light is lit. So that explains why that was happening.

Truly the only way to find out what's wrong is to get it scanned. I don't have a home scanner either, so I know it sucks to have to pay $45 to get a stupid code scanned, but it sure is helpful to know what you're dealing with -and in your case I would guess the code is coincidental to the IAT mod you did -that or you bumped something, or didn't hook it back up correctly. Otherwise I'd bet they're unrelated.

 

The SES might be a coincidence. Ignoring the work you did, for a moment, I would check the AIR pump fuse first. If ok, then recheck the wiring you touched.

 

sounds like the coolant temp sensor is unplugged or false contact. pull the air duct off and inspect the sensor, harness.
its screwed into the water pump.