P1520 moderate

Intake Manifold Runner Control Circuit Malfunction (Ford)

The P1520 code means the vehicle's onboard diagnostic system has detected: Intake Manifold Runner Control Circuit Malfunction (Ford). This is a moderate severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
moderate
Estimated cost
$60 - $400 (parts and labor)

Manufacturer-specific code. P1520 is a manufacturer-specific DTC, so its exact definition can differ by make, model, and year. Use the meaning above as a general guide, and always confirm it against your vehicle manufacturer's official service information (or a make-specific scan tool) before diagnosing or replacing parts.

What Are the Symptoms of P1520?

  • Check Engine Light illuminated
  • Slight loss of power at certain RPM ranges
  • Poor fuel economy
  • Engine may lack mid-range torque
  • Slight idle roughness

What Causes P1520? (Most Likely First)

  • Faulty IMRC solenoid Very High
  • Corroded IMRC circuit connector High
  • Open or shorted wiring in the IMRC circuit Moderate
  • Failed IMRC actuator Moderate
  • PCM output circuit failure Low

Can I Still Drive with P1520?

Yes, but fix soon. P1520 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.

Frequently Asked Questions

What is the IMRC solenoid?

The IMRC solenoid is an electrical valve controlled by the PCM that directs vacuum or electrical signals to the IMRC actuator, which physically moves the intake runner plates.

Can I drive safely with P1520?

Yes. The vehicle is safe to drive. Performance may be slightly reduced in certain RPM ranges, and fuel economy may suffer slightly. This is not an urgent repair.

Is this a common Ford issue?

Yes, particularly on the 4.6L and 5.4L modular V8 engines. IMRC solenoids and actuators are common wear items on these engines, especially after 100,000 miles.

Mechanics Guide Step-by-step diagnosis

How Do You Diagnose P1520?

  1. Test the IMRC solenoid resistance with a multimeter. Compare to the specification.

  2. Check the solenoid connector for corrosion, bent pins, or moisture.

  3. Verify the PCM output signal at the solenoid with a test light or multimeter.

  4. Inspect the wiring between the PCM and IMRC solenoid for damage.

  5. Command the IMRC with a scan tool and monitor the response.

P1520 on Diesel, EV & Equipment

The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:

PACCAR moderate SCR Outlet NOx Sensor Circuit

Which Vehicles Commonly Get P1520?

  • 1999-2004 Ford Mustang 4.6L
  • 2002-2010 Ford Explorer 4.6L
  • 2004-2010 Ford F-150 4.6L/5.4L
  • 2003-2011 Mercury Grand Marquis 4.6L
  • 2005-2010 Ford Expedition 5.4L

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