Engine Overheating When Idling – What’s Causing It and How to Fix?
Quote from AutoFixerMike on June 10, 2025, 3:24 pmHi DIYers,
My 2011 Honda Accord's engine overheats when idling for a few minutes, especially in traffic. But as soon as I start driving, the temperature drops back to normal. Coolant level seems fine, and there are no leaks. What could be causing this, and how do I fix it myself?
Hi DIYers,
My 2011 Honda Accord's engine overheats when idling for a few minutes, especially in traffic. But as soon as I start driving, the temperature drops back to normal. Coolant level seems fine, and there are no leaks. What could be causing this, and how do I fix it myself?
Quote from Kevin Nicholas on June 10, 2025, 3:42 pmIf your car engine is overheating at idle but cools down while driving, here are the most likely causes and DIY solutions:
🔍 Possible Causes:
Faulty radiator fan – Electric cooling fans help cool the engine when the vehicle isn’t moving. If the fan doesn’t turn on at idle, the engine overheats.
Bad fan relay or temp sensor – These control when the radiator fan activates. If faulty, fan won’t run.
Clogged radiator – May not circulate coolant efficiently.
Low coolant flow due to bad water pump or stuck thermostat – Especially if it’s old.
Air pockets in the cooling system – After coolant change, trapped air can block flow.
🛠️ DIY Fixes:
With engine cool, check if radiator fan spins when AC is on or engine gets hot.
Test the coolant temperature sensor using a multimeter or scanner.
Bleed the cooling system to remove trapped air.
Inspect for thermostat stuck closed – Replace if needed.
Check radiator for debris or rust buildup – flush it if necessary.
Also, try scanning with an OBD2 scanner to monitor real-time coolant temps and fan status. Good luck and let us know what worked!
If your car engine is overheating at idle but cools down while driving, here are the most likely causes and DIY solutions:
🔍 Possible Causes:
-
Faulty radiator fan – Electric cooling fans help cool the engine when the vehicle isn’t moving. If the fan doesn’t turn on at idle, the engine overheats.
-
Bad fan relay or temp sensor – These control when the radiator fan activates. If faulty, fan won’t run.
-
Clogged radiator – May not circulate coolant efficiently.
-
Low coolant flow due to bad water pump or stuck thermostat – Especially if it’s old.
-
Air pockets in the cooling system – After coolant change, trapped air can block flow.
🛠️ DIY Fixes:
-
With engine cool, check if radiator fan spins when AC is on or engine gets hot.
-
Test the coolant temperature sensor using a multimeter or scanner.
-
Bleed the cooling system to remove trapped air.
-
Inspect for thermostat stuck closed – Replace if needed.
-
Check radiator for debris or rust buildup – flush it if necessary.
Also, try scanning with an OBD2 scanner to monitor real-time coolant temps and fan status. Good luck and let us know what worked!
Quote from ScanToolGuru on June 10, 2025, 7:57 pmHappened to me last summer. The radiator fan relay was bad. Swapped it out for $10 and overheating at idle stopped. Easy fix!
Happened to me last summer. The radiator fan relay was bad. Swapped it out for $10 and overheating at idle stopped. Easy fix!
Quote from LadyGreaseHands on June 10, 2025, 8:08 pmDon’t underestimate air pockets! I had this exact issue after flushing my system. Did a proper coolant bleed and the problem disappeared.
Don’t underestimate air pockets! I had this exact issue after flushing my system. Did a proper coolant bleed and the problem disappeared.
Quote from CarGuyBrad on June 11, 2025, 1:28 pmMy fan was fine, but thermostat was stuck partially closed. It only overheated at idle. New thermostat fixed it for good.
My fan was fine, but thermostat was stuck partially closed. It only overheated at idle. New thermostat fixed it for good.