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Q: I have a problem with the temperature gauge - 2002 Buick Rendezvous

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I'm working on a 2002 Buick rendezvous. During normal warm up the temperature gauge goes up past the half point and stops midway between 1/2 and 3/4. At that point the cooling fan comes on and the gauge goes back to 1/2. My scanner reads the engine gets to 222 degrees when the fans come on then it reads 213 when the fan goes off. My question is why the gauge is reading so high or is this a normal reading or position from the gauge? I'm sure the scanner is accurate.

My car has 140000 miles.
My car has an automatic transmission.

Hello. The temperature gauge is going to elevate based on the resistance of the sensor. The first thing to check is the temperature sending unit. The wires or the sensor itself may be corroded or damaged. This would cause extra resistance in the system and cause the gauge to be off.

You can test the readings coming from the temperature sensor. You will want to test for resistance and match it to the correlated temperature. You can find these specifications based on make and model. This would inform you of what the gauge thinks the temperature is versus what the scanner is reading. If they are off, then you know the sensor is bad and you should replace it. The sensor will signal the computer as to when the fans should be turning on. If the fans are not turning on soon enough, this would be the cause.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to determine if the gauge is faulty and replace the temperature sending unit if necessary.

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