Idle Air Control Valve 2 Short / Open Circuit


Table of contents

P1509 MAZDA Possible Causes

  • Faulty Idle Air Control (IAC) valve
  • IAC valve stuck closed
  • IAC valve harness is open or shorted
  • IAC valve circuit poor electrical connection

How do I fix code P1509 MAZDA?

  Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.

Cost of diagnosing the P1509 MAZDA code

  The cost of diagnosing the P1509 MAZDA code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1509 MAZDA Description

  The Idle Air Control Valve (IACV) valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The Powertrain Control Module (PCM) determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM.

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