Intake Manifold Runner Control Circuit Malfunction (Ford)
What does P1520 mean?
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.
Common Symptoms
- Check Engine Light illuminated
- Slight loss of power at certain RPM ranges
- Poor fuel economy
- Engine may lack mid-range torque
- Slight idle roughness
Probable Causes (Ranked by Likelihood)
- 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
Step-by-Step Diagnostic Procedure
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Test the IMRC solenoid resistance with a multimeter. Compare to the specification.
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Check the solenoid connector for corrosion, bent pins, or moisture.
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Verify the PCM output signal at the solenoid with a test light or multimeter.
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Inspect the wiring between the PCM and IMRC solenoid for damage.
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Command the IMRC with a scan tool and monitor the response.
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.