P1506moderate severityPowertrain
Idle Air Control System Overspeed
on 2000 Mazda Protege 1.6L I4 · FWD
What this code means
The engine idle speed is too high. The PCM has detected that idle RPM exceeds the target and the IAC system cannot reduce it to the commanded speed.
Symptoms
- Check Engine Light
- Idle speed too high
- Vehicle creeps forward in gear
- Engine races at idle
Common causes
- Vacuum leak allowing unmetered air
- IAC valve stuck open
- Throttle body carbon preventing plate closure
- Faulty IAC valve
- Intake manifold gasket leak
Diagnostic steps
- Check for vacuum leaks with smoke test
- Inspect throttle body for carbon buildup preventing closure
- Disconnect IAC and check if idle drops
- Clean throttle body
- Inspect intake manifold gaskets
Repair notes
Find and repair vacuum leaks; clean the throttle body; replace the IAC valve if stuck open.
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