Idle Air Control System Overspeed
1990-1998 Mazda MPV 3.0L V6
Description
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.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P1506 on Other Vehicles
Common Questions
What does code P1506 mean on a 1990-1998 Mazda MPV?
P1506 stands for "Idle Air Control System Overspeed". 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.
What are the symptoms of P1506 on a Mazda MPV?
Common symptoms of P1506 include: Check Engine Light, Idle speed too high, Vehicle creeps forward in gear, Engine races at idle.
What causes P1506 on a 1990-1998 Mazda MPV?
Common causes of P1506 include: Vacuum leak allowing unmetered air, IAC valve stuck open, Throttle body carbon preventing plate closure, Faulty IAC valve, Intake manifold gasket leak.