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P codepowertrainMedium severity

P245AExhaust Gas Recirculation Cooler Bypass Control Circuit/Open

The PCM has detected an open or general fault in the control circuit for the EGR cooler bypass valve.

Definition

Diesel engines with cooled EGR use a bypass valve so exhaust gas can skip the cooler during warm-up, helping the engine and aftertreatment reach temperature quickly. The PCM monitors the bypass actuator's control circuit—usually a vacuum solenoid or electric actuator—and sets P245A when it detects an open circuit or no electrical load where one is expected. The engine runs normally in most cases, but the MIL illuminates, cold-start emissions increase, and a bypass stuck in the wrong position can cause EGR temperature or cooling-performance faults.

Common causes

  • Open wiring or broken connector terminal in the bypass solenoid circuit
  • Failed EGR cooler bypass vacuum solenoid or electric actuator coil
  • Corrosion in the connector causing an open connection
  • Blown fuse or open feed circuit supplying the solenoid
  • Harness damage from heat or rodents near the engine
  • Faulty PCM driver circuit (rare)

Common misdiagnoses

  • EGR valve replaced when the fault is the separate bypass actuator circuit
  • EGR cooler replaced for what is an electrical control fault
  • PCM replaced before checking the solenoid coil and wiring
  • Vacuum lines replaced when the electrical circuit is open

Troubleshooting steps

  1. 1.Command the bypass with a scan tool

    Use bidirectional control to actuate the EGR cooler bypass and listen/watch for solenoid click or linkage movement.

  2. 2.Check power at the solenoid connector

    With key on, verify battery or switched voltage on the feed terminal; no voltage means an open fuse or feed wire upstream.

  3. 3.Measure the actuator coil resistance

    Compare against spec (typical solenoids read roughly 20-80 ohms); an open (OL) reading condemns the actuator.

  4. 4.Verify control-wire continuity to the PCM

    With the battery disconnected, confirm under 1 ohm from the solenoid control terminal to the PCM pin and no short to ground or power.

  5. 5.Confirm mechanical operation after repair

    Re-command the bypass and verify the valve actually moves through its travel; then clear codes and confirm the fault does not reset.

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