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P1520

Intake Manifold Runner Control Circuit Malfunction.

  • Other
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
20
FaultThe specific fault in that area

What it means

P1520 is a manufacturer-specific code, so its meaning depends on the make. For this entry it is read as an Intake Manifold Runner Control circuit malfunction. The engine control unit saw an electrical fault in the runner control circuit, or the runner position did not match what it commanded. Confirm the exact definition for the vehicle's make and model before diagnosing.

Symptoms

  • Engine warning light on
  • Loss of power, especially at mid to high revs
  • Poor low-speed torque or flat spot on acceleration
  • Rough or unstable idle
  • Poorer fuel economy
  • Whistling or rattling from the intake manifold on some engines

Possible causes

  • Faulty runner control solenoid, motor or actuatorlikely
  • Damaged wiring or poor connector contact in the runner control circuit (open, short or high resistance)likely
  • Runner flaps or linkage seized, carboned up or broken, so the position does not match the commandpossible
  • Vacuum leak, split hose or failed vacuum reservoir on vacuum-operated systemspossible
  • Faulty runner position sensor or its feedback circuit, where fittedpossible
  • Fault in the engine control unit driver circuitrare
  • Outdated control unit software where the manufacturer lists it as a known causerare

How to diagnose

  1. Confirm the manufacturer's definition of P1520 for this make, model and engine, and note whether the system is vacuum, solenoid or motor operated
  2. Read all stored codes and freeze frame data, and check for related codes such as runner position or vacuum faults
  3. Visually inspect the wiring, connectors and vacuum hoses at the actuator and solenoid for chafing, corrosion, heat damage and splits
  4. Check the supply voltage and earth at the actuator or solenoid connector with the ignition on
  5. Command the runner control with a scan tool, if supported, and watch or listen for movement and any position feedback change
  6. Measure solenoid or motor resistance and compare it with the manufacturer's specification
  7. Check the flaps, shaft and linkage for free, full-range movement and for carbon build-up or broken parts
  8. Check for manufacturer service bulletins or software updates relating to this code on the vehicle

How to fix

  • Repair or replace damaged wiring and clean or replace faulty connectors
  • Replace the faulty runner control solenoid, motor or actuator
  • Clean or replace seized, carboned or broken runner flaps or the affected manifold section as the design requires
  • Replace split or disconnected vacuum hoses and any faulty vacuum reservoir or check valve
  • Replace a faulty runner position sensor
  • Apply a manufacturer-issued software update only where a bulletin identifies an outdated calibration as the cause

Can I keep driving?

Medium severity

The car can usually be driven for a short time with reduced performance, but get it checked soon. On some engines a broken runner flap or its fixings can enter the engine, so stop driving and investigate if you hear rattling or power drops sharply.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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