My engine temperature gauge suddenly stopped working about a month ago. I drove to work and when I was going to lunch, I noticed the needle just stayed at cold and it hasn't moved since.

I've read a few threads but I'm pretty stumped. I've already disconnected the battery but the needle is still dead. Car drives absolutely fine, no start up issues when hot or cold, both AC and heat work perfectly, no CEL, it's just that darn needle.

Anyone know how to isolate the problem? I hate seeing that lazy needle and I think it may be affecting my gas mileage.

 

Perhaps try a PM to the Tannin auto guy here, he may have some suggestions that help out.

 

it wont affect your gas mileage because it is simply an indicator signal. the ECU gets it's temperature reading from the two wire sensor right next to the 1 wire sensor.

 

Does the needle not move at all or does it go up about a 1/4 and stop. You might want to check your thermostat and make sure it's not stuck open. That's what happen to me.

 

The needle is dead. It doesn't move.

 

So what could be wrong? If the gauge sensor is broken, is it possible the other sensor is broken as well?

Do I take the sensor out and put it in hot water to see if it's still working?

 

you go look on the front of the motor, on the passenger side front there are two sensors in the coolant passage, you can use a multimeter to check their resistance when the engine is hot and cold, to verify that the sensor is working correctly. i don't have the resistance values off hand but you can search for them.

with the two wire sensor you just measure across the two contacts, with the single wire sensor you reference anywhere metal on the engine for ground.

with the single wire sensor (that goes to the gauge cluster) there is a good chance that something is wrong with the gauge cluster though, which is more work. start by checking the sensor and the plug going from it first.

 

Do you know if the 300 and 400 are different?