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Home/DTC Codes/Lincoln/MKX/2016-2018 3.7L V6/P1504
P1504

Idle Air Control Circuit Malfunction

2016-2018 Lincoln MKX 3.7L V6

Moderate SeverityPowertrain

Description

The Idle Air Control (IAC) valve circuit has a malfunction. The IAC valve controls engine idle speed by regulating the amount of air bypassing the throttle plate.

Symptoms

  • Check Engine Light
  • Erratic idle speed
  • Idle too high or too low
  • Engine stalling at idle
  • Rough idle

Common Causes

  • Faulty IAC valve
  • Carbon buildup on IAC valve or throttle body
  • Wiring issue to IAC
  • Vacuum leak affecting idle
  • Dirty throttle body

Diagnostic Steps

  1. Test IAC valve resistance
  2. Clean IAC valve and throttle body
  3. Inspect IAC wiring and connector
  4. Check for vacuum leaks
  5. Monitor IAC duty cycle on scan tool (should be 22-65%)

Repair Notes

Clean throttle body and IAC valve first. Replace IAC if faulty. Repair vacuum leaks.

Related Codes

P0505Idle Air Control SystemP1505IAC Valve Opening Coil Circuit OpenP1505Idle Air Control System at Adaptive LimitP1505Idle Air Control System at Adaptive LimitP1505Idle Air Control System at Adaptive LimitP1505IAC Valve Opening Coil Circuit OpenP1505IAC Valve Opening Coil Circuit OpenP1506IAC Valve Opening Coil Circuit ShortP1506Idle Air Control Overspeed ErrorP1506Idle Air Control Overspeed ErrorP1506Idle Air Control Overspeed ErrorP1506IAC Valve Opening Coil Circuit ShortP1506IAC Valve Opening Coil Circuit ShortP1506Idle Air Control System OverspeedP1507Idle Control System Malfunction Fail SafeP1507IAC Valve Closing Coil Circuit OpenP1507Idle Air Control Underspeed ErrorP1507Idle Air Control System UnderspeedP1507IAC Valve Closing Coil Circuit OpenP1507Idle Air Control Underspeed ErrorP1507IAC Valve Closing Coil Circuit OpenP1507Idle Air Control Underspeed Error

Other Powertrain Codes

P1504 on Other Vehicles

Lincoln Aviator

2003-2005 4.6L V8

Lincoln Aviator

2003-2005 4.6L V8 DOHC

Lincoln Aviator

2020-2024 3.0L Twin-Turbo V6

Lincoln Aviator

2020-2024 3.0L V6 Twin Turbo

Lincoln Aviator Grand Touring

2020-2024 3.0L Twin Turbo V6 PHEV

Lincoln Aviator Grand Touring

2020-2024 3.0L Twin-Turbo V6 Hybrid

Lincoln Aviator Grand Touring

2020-2024 3.0L V6 Twin Turbo Hybrid

Lincoln Blackwood

2002-2002 5.4L V8

Common Questions

What does code P1504 mean on a 2016-2018 Lincoln MKX?

P1504 stands for "Idle Air Control Circuit Malfunction". The Idle Air Control (IAC) valve circuit has a malfunction. The IAC valve controls engine idle speed by regulating the amount of air bypassing the throttle plate.

What are the symptoms of P1504 on a Lincoln MKX?

Common symptoms of P1504 include: Check Engine Light, Erratic idle speed, Idle too high or too low, Engine stalling at idle, Rough idle.

What causes P1504 on a 2016-2018 Lincoln MKX?

Common causes of P1504 include: Faulty IAC valve, Carbon buildup on IAC valve or throttle body, Wiring issue to IAC, Vacuum leak affecting idle, Dirty throttle body.

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