Thread: Coolant Temperature Sensor

So, the temperature gauge bottoms out, and the DIC says "A/C off due to emgine temteratures," or some such. Having been though this with the Monte, where I broke the connector in the process of changing the #1 spark plug, I deduced it was the coolant temperature sensor, and replaced it. Start the car, still no temperature reading, same DIC message.

Did I get a defective sensor, or could something else be wrong? The current connector seems just fine.

Is it a aftermarket coolant temp sensor? When I had my 98 GTP I changed the sensor with a aftermarket one and it never read correctly. Swapped it out for a AC Delco one same day and it was good again. I believe the wire harness for it is just a short piece that can be unplugged at both ends and removed from the car. Take it off and remove the old factory wire loom/tape and check it out if you haven't already.

It wasn't the ambient temperature sensor; that wouldn't cause the gauge to bottom out. The coolant sensor magically started working after four key cycles. Who's the genius who designed THAT system?

Originally Posted by Scottydoggs

new temp sensors are known to be junk, so either its bad already, or its little harness there is cooked up.

If they're all junk, why does anyone replace them? I mean, I live in Florida and I'm married, so I have no choice, but why does anyone else?

Originally Posted by Scottydoggs

ive seen ppl here replace 2 in a row that were new and dead in the box. and you need that sensor, it controls the cooling fans and sends info to the dash temp gauge. its a two part sensor, one side to the pcm, other to the dash. why the dash will still read but fans quit, or vs versa.

So there are two signals produced within the sensor itself instead of being split off ? That could make it more tricky to troubleshoot should there be a problem. I recently suspected my CTS, but after troubleshooting, it seems to be OK. I don't have a heating problem, the dash temps appear normal, and the fans kick on at about the 3/4 mark on the dash. One thing that I can't explain is that when I disconnected the CTS, the fans immediately turned on. I read elsewhere on this forum that if the fans start after the CTS is disconnected, that indicates a bad CTS. Mine does that, but the cooling fans seem to be functioning normally.