04 GTP Temp Gauge

In the midst of all of the upgrading that I am planning on doing my GP is having some problems. My is a daily driver and my only vehicle right now so hopefully this isn't a big problem. Anyways, I was driving today and temp gauge was working fine for about 20-30 miles running at my normal temperatures and then it just dropped to where it is when the car is off. I noticed that my fan was running when I parked it to check it out. I plan on taking it to the dealership tommorow to figure out what is wrong with it, but I am trying to get an idea from you all first. All I have on the car is a SLP catback system and a K&N CIA which makes me wonder about what the dealership is going to tell me about my factory warranty. Should I just not take it to the dealership? There is no way that I could put the stock air box back in with tools that I have in my house. Any guess as to what I should tell the dealer if they give me some problems.

For the dealer to not honor your warranty would be uncalled for considering the exhaust and intake mods probably have nothing to do with your problem but you never know. The temperature gauge works off of the engine coolant temperature sensor (ECT). The PCM works off it too to determine if the car has come up to proper operating temperature and control the cooling fans, etc. For now check the electrical connections to the ECT sensor and make sure it's tight and contact is good. I'd take it to the dealer if you are still under the warranty. It's easy for the dealer to check that circuit with a Tech II machine.

Per the Magnuson-Moss Warranty Act is is illegal for the dealer not to honor the warranty unless THEY can prove the mods caused the problem. Good luck!

Logically, the mods that I put on my car shouldn't have anything to do with the error that I'm getting right? The car is still running like normal.

Well, there was no need to take it to the dealership because it fixed its self. Just to be on the safe side, does anyone know where the ETC sensor is at so that I can check and see if it is in their nice and tight?

Well, there was no need to take it to the dealership because it fixed its self. Just to be on the safe side, does anyone know where the ETC sensor is at so that I can check and see if it is in their nice and tight?


I'm not sure about your Series III engine but on a Series II the ECT, engine coolant temperature sensor is located about 3 inches below the thermostat and housing. Its got a standard GM electrical connector. Just follow the upper radiator hose towards the engine and thermostat. From there look down approx. 3 inches and hopefully you'll see it.

Thanks... I'll try to find it when I go home.