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P codepowertrainMedium severity

P032DKnock Sensor 3 Circuit High (Bank 1)

The knock sensor 3 circuit on bank 1 is reading a higher voltage than the PCM considers possible.

Definition

The PCM feeds a bias voltage through the knock sensor 3 circuit and watches for the small AC signal the piezoelectric element superimposes on it; P032D sets when the circuit voltage sticks above the valid window, which indicates an open circuit or a short to voltage rather than a noisy engine. With the input invalid, the PCM disables knock control for that sensor and runs retarded base timing, illuminating the MIL and costing some power and fuel economy. Because detonation on the affected cylinders is no longer detected, sustained heavy-load operation should be avoided until it is repaired.

Common causes

  • Open circuit in the sensor wiring or connector (broken wire, backed-out terminal)
  • Knock sensor internally open
  • Signal wire shorted to a voltage source after harness damage
  • Corrosion creating an open at the sensor or PCM connector
  • PCM input circuit fault (rare)

Common misdiagnoses

  • Replacing the knock sensor when the harness is open
  • Replacing the PCM
  • Replacing ignition components for suspected detonation
  • Swapping sensors without repairing the chafed wiring that caused the short

Troubleshooting steps

  1. 1.Check the bias voltage at the sensor connector

    Backprobe key-on/engine-off and compare to spec (commonly around 2.5 V on biased circuits); battery-level voltage indicates a short to power, while an out-of-range reading with the sensor unplugged isolates harness vs. sensor.

  2. 2.Test for an open circuit

    With both ends disconnected, check continuity of the signal and return wires end to end; infinite resistance confirms a harness open.

  3. 3.Measure sensor resistance

    Compare the sensor's resistance to the service spec (resistor-type units often read ~100 kΩ); an open (OL) reading condemns the sensor.

  4. 4.Inspect the harness route

    Trace the wiring for melted insulation near exhaust components or chafe points where it could contact a powered circuit.

  5. 5.Repair, clear, and verify

    After repair, confirm the circuit voltage returns to the normal bias window and the code does not reset over a warm-engine drive cycle.

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