P0509 OBD-II: Idle Air Control System Circuit High
P0509 Severity
Should you fix P0509 yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P0509?
The Idle Control System manages the engine idle speed. To raise or lower the engine Idle speed, the engine control module (PCM), opens or closes the Idle Air Control valve to allow more or less air into the engine. When the PCM cannot achieve the desired RPM, it will set code P0509.
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