Q: Car is idling at low speed my check engine light came on

Hi Johnny. There are several components that can cause a low engine idle, and trigger the check engine light from idle control valves, throttle body itself, fuel injectors, mass air flow sensor and more. The light itself is activated when an error code is created by a sensor that detects a fault with a system or individual part. A professional mechanic would begin the diagnostic process by downloading these error codes from the ECU and determining where the fault is coming from. Once they have a place to start, they manually complete an engine idle inspection to locate the exact source of this problem and recommend the right repairs.