Skip the auto shop - Our mechanics make house calls

Q: Having problems with temperature gauge

asked by on

My car normally runs perfectly, but if it sits still for a few minutes, the temperature gauge goes up and I get a warning light. If the car is moving, the gauge is normal. If I turn on the heat full-blast, the gauge drops to normal. It hasn't actually steamed up yet or given any other indication, but when I catch it happening I either turn the car off, or turn on the heater. The car is due for an oil change, but the level is fine and it doesn't look terrible. The coolant was low. I can't really say how low exactly, but about the capacity of the reservoir. However, adding coolant hasn't changed anything. Also, I haven't caught it leaking anything yet. The radiator fans are running. I don't know if this could be relevant, but this has been happening more or less since I recharged the A/C. The A/C hadn't been working for almost as long as we've owned the car, about three years. But turning the A/C on or off makes no difference. Any ideas?

A: The only way to determine the root cause of...

The only way to determine the root cause of your problem is to have the vehicle's warning light inspected firsthand by a professional, such as one from YourMechanic.

An engine that is running hot is less likely to overheat when it is moving because cool air is being pushed through the radiator at the front of the vehicle. Likewise, turning on the heater draws heat out of the engine compartment and into the interior of the vehicle.

The first thing that comes to mind is the engine cooling fan, since a failed fan would be the most likely cause of a vehicle that overheats at idle, but not while moving. But since you said the fan is working, I would look at the water pump next. Since it is driven off the engine, the water pump flows more at higher RPMs. This is just a guess though, and really, any part of your cooling system could be to blame.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Tire question

The manufacturer's original tire size is P235/45R18. Unfortunately, the 215/65R16 tires will not fit. The rim size on these is 16 inches and your car is equipped with 18 inch rims. The tire size is different as well. The only...

Q: loud humming noise front in passenger side

It sounds like your humming noise is likely a bad wheel bearing or tire. I would lean more towards a bad wheel bearing. A visual inspection can easily determine where the noise is coming from in this case. Keep in...

Q: Random transmission slipping?

Sounds like you have a fluid pressure problem which could be related to an internal solenoid to the transmission, low fluid, or a bad torque converter/fluid pump. An engine/transmission code scan with an advanced scan tool is needed in order...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...