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P codepowertrainMedium severity

P245DExhaust Gas Recirculation Cooler Bypass Control Circuit High

The control circuit for the EGR cooler bypass valve is showing higher voltage than expected for the commanded state.

Definition

The PCM drives the EGR cooler bypass actuator (typically by grounding a solenoid control wire) and monitors the circuit voltage to confirm the command took effect. P245D sets when the control circuit voltage is high when it should be pulled low—pointing to a short to voltage, an open in the driver's ground path, or a failed actuator. The MIL illuminates and the bypass may be stuck in one position, which can slow engine/aftertreatment warm-up or cause EGR cooling-performance codes, but immediate driveability impact is usually minor.

Common causes

  • Control wire shorted to battery or switched voltage
  • Failed bypass solenoid/actuator with an internally shorted or open winding
  • Corroded connector terminal creating high resistance in the control circuit
  • Chafed harness contacting a power feed near the engine
  • Faulty PCM low-side driver (rare)

Common misdiagnoses

  • EGR valve replaced when the bypass actuator circuit is at fault
  • EGR cooler replaced for a purely electrical circuit-high condition
  • PCM replaced before ruling out a harness short to voltage
  • Battery/charging system blamed for a localized circuit fault

Troubleshooting steps

  1. 1.Verify the fault electrically

    Back-probe the control wire; with the PCM commanding the bypass on, the wire should pull near 0 V—if it stays at supply voltage the driver's command isn't reaching ground.

  2. 2.Test the actuator coil

    Measure solenoid resistance against spec (commonly 20-80 ohms); replace the actuator if open or far out of range.

  3. 3.Check for a short to voltage

    With the connector unplugged and key on, the control wire should show no voltage; any reading indicates a harness short to a feed circuit.

  4. 4.Inspect the harness and connector

    Trace the circuit for melted insulation, chafe points against brackets, and corroded or spread terminals.

  5. 5.Bench-actuate and confirm repair

    Apply power and ground to the solenoid to verify it clicks and flows/blocks vacuum correctly, then re-command with the scan tool and confirm the code does not reset.

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