Overheating when in traffic or stopped at red lights

Hi Sharon,

The most likely cause is the cooling fan is not running or not running at the high speed when in traffic.

Unfortunately, the only way to really verify this without a scan tool is to monitor it when the vehicle begins to overheat. We need to listen for the fan to see if it is on. Then we need to hear if it is increasing in speed. When it increases in speed it is very obvious change. So preferable we would need to listen to it when it first comes on and then continue to stand there and wait for it to roar louder when the engine temp comes up. If it is coming up and the needle on your dash gets past half way, it should be in the high speed by then. If you have not heard it get louder, then you are missing your second stage.

At this point we can go further with the diag. However, if you have both stages then it is something else. Possibly a blockage in the cooling system or restricted air flow.

I am pretty confident that this is a fan issue because of the way you described it. The fact that it only does it sitting still but is fine when you are moving faster. If you think about it, the purpose of the fan is to move air over/through the radiator so that it cools the coolant down that is inside of the radiator. Then the cooling system moves that cooler coolant through the engine. When you are not moving we still need air to move through the radiator to cool the coolant which is what the fan does. When you are moving the fan is not as needed.

Here are some articles on this stuff. Let me know what you find and we can go from there. Thanks

https://www.2carpros.com/articles/engine-cooling-system

https://www.2carpros.com/articles/how-an-electric-cooling-fan-works