1999 Audi A4 Temp Gauge Slow to Rise

AUDI A4
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BOSNIANAC
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  • 7 POSTS
hi , I just bought Audi A4 1999 turbo 4 cy with 72000 miles on it and the problem is that the temperature gauge takes long time like 30 - 40 min to rise to normal level that's when the car is at rest and when I start driving it stays at normal level for some time and then falls on C, is it possible that thermostat is stuck open also the fan the one behind the grills runs all the time when car is on.please help thanks.
Feb 26, 2006 at 4:30 AM
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PEPPERMRJ
  • ✓Experienced Mechanic
  • 1,158 POSTS
If the fan is constantly running that is why your temp gauge is slow to reach normal operating temperature. How is the heat in the cabin?

Normally the computer controls the running of the electric cooling fan based on the input of the coolant temperature sensor. It sends power to the relay, which in turn completes the circuit, thus starting the cooling fan.
I would check for a stuck relay, a wire shorted to 12 volts, or a bad engine coolant temperature sensor. Most autos turn the cooling fan on when the airconditioning is on also.

Good hunting and let us know. :)
Feb 26, 2006 at 6:02 AM
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BOSNIANAC
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  • 7 POSTS
heating works fine and everything else, i also have heated seats and that works fine to so the only thing is the temp gauge.
Feb 27, 2006 at 11:54 AM
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BOSNIANAC
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  • 7 POSTS
hey guys i fixed the problem it was faulty thermostat it was stuck open just like I thought, thanks anyways for help you offered, by the way i think that this is the most useful and best web about car repair that you can find on internet.

keep it up :D
Mar 2, 2006 at 10:40 AM
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Suggested Repair

Replace the thermostat if it is stuck open, which the owner confirmed fixed the slow warm-up and gauge drop. Because the cooling fan ran constantly, also check for a stuck fan relay, a wire shorted to 12 volts, or a faulty engine coolant temperature sensor.

Conversation Summary

The owner of a 1999 Audi A4 said the temperature gauge took 30 to 40 minutes to reach normal at rest, then dropped to cold while driving, and the radiator fan ran whenever the car was on. Cabin heat worked normally. An expert explained that a constantly running fan can prevent normal warm-up and suggested checking a stuck fan relay, a wire shorted to 12 volts, or a bad coolant temperature sensor. The owner later reported that a thermostat stuck open was the cause and that fixing it solved the problem.

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