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2017 MAZDA MAZDA3
2.5L I4•FWD•AUTOMATIC•gas
2 active safety recalls on this vehicle — view recalls
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Repairs0Labor492Torque3331Fluid7DTC1130Battery1Maintenance0Recalls2
P1506moderate severityPowertrain

Idle Air Control System Overspeed

on 2017 Mazda Mazda3 2.5L 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

  1. Check for vacuum leaks with smoke test
  2. Inspect throttle body for carbon buildup preventing closure
  3. Disconnect IAC and check if idle drops
  4. Clean throttle body
  5. Inspect intake manifold gaskets

Repair notes

Find and repair vacuum leaks; clean the throttle body; replace the IAC valve if stuck open.

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