P0509moderate severityPowertrain
Idle Air Control System Circuit High
on 2004 Mazda MX-5 Miata 1.8L I4 · RWD
What this code means
High voltage in IAC circuit.
Symptoms
- High idle
- Racing idle
Common causes
- Short to power
- Faulty IAC motor
- Open ground
Diagnostic steps
- Test IAC voltage
- Check for shorts to power
Repair notes
Replace IAC or repair wiring.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1