2001 grand prix new coolant temp sensor problem

The temperature gauge was recently misbehaving so I decided to change the engine coolant temperature sensor on my 01' grand prix 3800. With the old sensor it went a few days reading nothing on the temp guage even though I was driving my car all day, it did this for two days. then all of a sudden it jumped to normal and started jumping up and down from cold to normal as I was driving. After i took it out and installed the new one it now reads the temperature in the red and im stumped... Anyone out there know whats going on?

nope. probably a problem with the gauge itself. we spent near 500 bucks tryin to figure out why mine was doin it.. we gave up and i drove it for 4 years like that. i never actually had any over heating problems. the gauge was just goofy

With the sensor unplugged and key in run the gauge should read it's lowest reading. With the connector jumped the gauge should peg hot. Even more precisely the sensor is 1,365ohms at 100 degrees F, and 44ohms at 280 degrees F. Are the terminals that plug into the sensor spread and creating intermittent contact? That would cause a jumpy gauge.

Did you use any teflon tape on the threads?

The sensor uses the threads as a grounding point for it, if you don't have a good contact you can have that kind of problems.

Oscar.

It would be best if you could monitor coolant temp. in the PCM data list with a scan tool and compare it to the reading on the cluster gauge. Did you replace a 2 wire sensor with black and yellow wires or a single wire sensor with a green wire?