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Home/DTC Codes/Lincoln/MKX/2016-2018 3.7L V6/P1506
P1506

Idle Air Control Overspeed Error

2016-2018 Lincoln MKX 3.7L V6

Moderate SeverityPowertrain

Description

The engine idle speed is too high. The PCM has detected that idle RPM exceeds the target idle speed and the IAC system cannot bring it down. The engine may be idling at 2000+ RPM.

Symptoms

  • Check Engine Light
  • Idle speed too high
  • Engine races at idle
  • Vehicle creeps forward in gear

Common Causes

  • Vacuum leak (most common)
  • IAC valve stuck open
  • Throttle plate not closing fully
  • Throttle body carbon buildup preventing closure
  • Faulty IAC valve
  • Intake manifold gasket leak

Diagnostic Steps

  1. Check for vacuum leaks with engine running — spray carb cleaner around intake
  2. Inspect throttle body for carbon preventing plate closure
  3. Test IAC valve — disconnect and check if idle drops
  4. Clean throttle body and IAC passages
  5. Inspect intake manifold gaskets

Repair Notes

Find and repair vacuum leak. Clean throttle body. Replace IAC valve if stuck open.

Related Codes

P0507Idle Air Control System RPM Higher Than ExpectedP1504Idle Air Control Circuit MalfunctionP1504Idle Air Control Circuit MalfunctionP1504Idle Air Control Solenoid Circuit IntermittentP1504Idle Air Control Circuit MalfunctionP1505Idle Air Control System at Adaptive LimitP1505IAC Valve Opening Coil Circuit OpenP1505IAC Valve Opening Coil Circuit OpenP1505Idle Air Control System at Adaptive LimitP1505IAC Valve Opening Coil Circuit OpenP1505Idle Air Control System at Adaptive LimitP1507Idle Air Control System UnderspeedP1507Idle Air Control Underspeed ErrorP1507Idle Air Control Underspeed ErrorP1507Idle Air Control Underspeed ErrorP1507IAC Valve Closing Coil Circuit OpenP1507IAC Valve Closing Coil Circuit OpenP1507IAC Valve Closing Coil Circuit OpenP1507Idle Control System Malfunction Fail Safe

Other Powertrain Codes

P1506 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 P1506 mean on a 2016-2018 Lincoln MKX?

P1506 stands for "Idle Air Control Overspeed Error". The engine idle speed is too high. The PCM has detected that idle RPM exceeds the target idle speed and the IAC system cannot bring it down. The engine may be idling at 2000+ RPM.

What are the symptoms of P1506 on a Lincoln MKX?

Common symptoms of P1506 include: Check Engine Light, Idle speed too high, Engine races at idle, Vehicle creeps forward in gear.

What causes P1506 on a 2016-2018 Lincoln MKX?

Common causes of P1506 include: Vacuum leak (most common), IAC valve stuck open, Throttle plate not closing fully, Throttle body carbon buildup preventing closure, Faulty IAC valve, Intake manifold gasket leak.

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