Q: Idle rough when engine warm.

asked by on May 16, 2016

Starts fine-once engine warms up car idles rough. Can not be driven until engine cools down.
My car has an automatic transmission.

There are a few possible problems that could cause these symptoms. It could have a failed coolant temperature sensor, which reports the temperature of the engine to the engine control module. The engine control module uses this info to determine how much fuel to inject for the given engine temperature. It could also have a failed manifold absolute pressure (MAP) sensor, or a bad intake air temperature sensor. I suggest having the system diagnosed by a qualified professional, such as one from YourMechanic, who can quickly and accurately diagnose the rough running and provide you with a suggested repair.

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