So for some reason, when my car is on and idle for awhile, the temperature gauge starts going up… When I drive, the temperature gauge goes down… Any idea what might be wrong? Or is this normal?
Can you verify that at some point in time the electric fans attached to your radiator run? can you verify that when your AC is on that these same electric fans always run?
How high will the temp go if you don’t start to drive? how fast is this rise in temp happening? (like does it go from the middle of the gague to the red section in the time it takes a stop and go light to go from red to green)?
How old is the car, and how many miles does it have?
This could indicate a problem with the radiator cooling fan(s). They should cycle on and off while the engine is idling to prevent temperature rise.
I’d check the fan fuses and make sure the radiator coolant level is correct (full).
You can verify the fans’ operation (or lack thereof) by opening the hood and watching the fans as the engine idles. The fans should cycle on and off, and the engine should not overheat.
DO NOT put your hands or anything else near the fans. They may come on at any time.
If the cooling system is working correctly the temperature gauge should move from cold to its normal position and not move from there except under extreme conditions.
Idling in traffic is not an extreme condition.
A thermostat stuck in the open position is another thing to consider. When you start the engine from cold, does it warm up quickly to normal temperature? Do you have any problems with interior heating?
So the temperature starts rising from a little below half way on the gauge to all the way to “H” between 5-7 mins of idle time. The fan kicks on when I turn my AC on but I don’t hear it when the car is idle.
It is an 06 Honda Civic SI with 70k miles on it. I believe I just had the thermostat and spark plugs replaced cuz the thermostat valve didn’t open or something? I just had coolant put into the car.
A few weeks ago, the overheating was a lot worse… It would rise with a minute of idle time.
Thanks for your time and effort.
There’s a temperature sensor mounted near the bottom of the radiator.
It’s either bad or the wire connector has come loose (I’ve seen that before on a Honda).
in some cars, esp. the older ones without electric fans, the temp will rise till the thermostat opens, then fall a little when you are rolling, but the difference in temp is not great.
I think you first need to pull the radiator cap (when cool) and make sure the radiator is full of coolant. It would also be a good idea to do a pressure test on the coolant system and cap.let us know.
The fact that the temp normalizes when you are driving means there is something wrong with the system controlling your fan. I don’t know enough about Honda Civics to tell you what to look for,but the fact that the fans come on with the a/c means that the fans themselves are fine. If you had a plugged radiator or bad water pump the car would overheat worse with driving.
Does the temp come down to normal if you idle it with the a/c on?