Possible causes
– Faulty Idle Air Control Valve
– Vacuum leak
– Idle Air Control Valve harness is open or shorted
– Idle Air Control Valve circuit poor electrical connection
– Vacuum leak
– Idle Air Control Valve harness is open or shorted
– Idle Air Control Valve circuit poor electrical connection
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0518 Information for specific makes
P0518 MAZDA