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P codepowertrainMedium severity

P20E1Exhaust Aftertreatment Fuel Pressure Sensor Circuit High

The signal from the exhaust aftertreatment fuel pressure sensor is stuck above its normal operating range, typically from a short to voltage or a broken ground.

Definition

The PCM expects the aftertreatment fuel pressure sensor signal to remain inside a fixed voltage window during all operating conditions. P20E1 sets when the signal exceeds the high threshold (commonly above about 4.5 V), which points to a short to battery or reference voltage, an open signal or ground wire, or an internally failed sensor. The PCM disables or distrusts dosing control, active DPF regeneration is inhibited, the MIL illuminates, and prolonged operation leads to high soot load and derate.

Common causes

  • Sensor signal wire shorted to reference or battery voltage
  • Open sensor ground circuit
  • Open signal wire on designs where the PCM pull-up drives the input high
  • Internally failed pressure sensor
  • Corroded connector terminals creating high resistance on the ground

Common misdiagnoses

  • Sensor replaced when the ground wire is open
  • HC doser or supply valve replaced for an electrical fault
  • PCM condemned without harness testing
  • Fuel system pressure regulators replaced needlessly

Troubleshooting steps

  1. 1.Confirm the stuck-high reading

    Key-on engine-off, the PID pegged at maximum pressure or ~5 V signal confirms a circuit fault rather than real pressure.

  2. 2.Unplug the sensor and observe the PID

    If the reading stays pegged high with the sensor disconnected, the fault is in the harness or PCM, not the sensor.

  3. 3.Check the sensor ground circuit

    Measure voltage drop from the sensor ground pin to battery negative with the key on; more than 0.1 V indicates a bad ground path.

  4. 4.Test the signal wire for shorts to voltage

    With the sensor unplugged, the signal wire should not carry battery or 5 V reference potential from an adjacent chafed circuit.

  5. 5.Replace the sensor if circuits test good

    Verify the repair by watching pressure track a commanded dosing event through a forced regeneration.

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