2017 MAZDA MX-5 MIATA

2.0L I4RWDMANUALgas
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P1504moderate severityPowertrain

Idle Air Control Solenoid Circuit Intermittent

on 2017 Mazda MX-5 Miata 2.0L I4 · RWD

What this code means

The PCM has detected an intermittent electrical fault in the Idle Air Control solenoid circuit. The IAC solenoid connection is making and breaking contact, causing erratic idle speed behavior.

Symptoms

  • Check Engine Light
  • Erratic idle speed
  • Idle fluctuates up and down
  • Intermittent stalling

Common causes

  • Loose IAC solenoid connector
  • Corroded IAC wiring or pins
  • IAC solenoid with intermittent coil fault
  • Damaged wiring near engine vibrating loose
  • PCM connector issue

Diagnostic steps

  1. Wiggle test IAC connector while monitoring idle speed
  2. Inspect IAC solenoid connector for corrosion or loose pins
  3. Test IAC solenoid resistance at various temperatures
  4. Check wiring for chafing or intermittent breaks
  5. Monitor IAC duty cycle for erratic changes

Repair notes

Repair the IAC connector or wiring; replace the IAC solenoid if it has an intermittent internal fault.

Other Powertrain codes on this vehicle

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