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P codepowertrainMedium severity

P0331Knock Sensor 2 Circuit Range/Performance (Bank 2)

The Bank 2 knock sensor is producing a signal, but its level or activity is outside the range the PCM considers plausible.

Definition

The PCM continuously compares each knock sensor's background output against expected values for the current RPM and load; P0331 sets when the Bank 2 sensor's signal is present but too weak, too strong, or inconsistent with conditions — the Bank 2 counterpart to P0326. The PCM responds by retarding timing as a precaution, causing mildly reduced power and fuel economy with the MIL on. Because a genuinely noisy engine can also push the sensor out of range, mechanical noise must be ruled out before condemning the sensor.

Common causes

  • Degraded or failing Bank 2 knock sensor
  • Incorrect sensor mounting torque or corrosion under the sensor's seat
  • Corroded connector or damaged shielded wiring attenuating the signal
  • Genuine engine mechanical noise on Bank 2 (piston slap, valvetrain clatter, rod knock)
  • Coolant or water intrusion at the sensor or connector
  • PCM input circuit fault (rare)

Common misdiagnoses

  • Sensor replaced when internal engine noise is driving the signal out of range
  • Bank 1 sensor replaced due to bank misidentification
  • Spark plugs replaced for fallback-timing power loss
  • PCM replaced before mounting torque and wiring are verified

Troubleshooting steps

  1. 1.Rule out real engine noise on Bank 2

    Listen with a stethoscope for knock, slap, or valvetrain noise on that bank — a mechanical problem will keep setting the code no matter how many sensors you install.

  2. 2.Inspect the Bank 2 sensor circuit

    Check the connector for corrosion or fluid, and trace the shielded cable for chafe points near the exhaust and bellhousing.

  3. 3.Reseat the sensor at correct torque

    Clean the mounting boss to bare, flat metal and torque to specification (commonly 15-25 Nm) — a corroded seat or wrong torque directly shifts signal amplitude.

  4. 4.Scope and compare both banks

    At matched conditions the two sensors should show similar AC activity; a Bank 2 trace that is flat or several times larger than Bank 1 isolates the fault.

  5. 5.Replace the sensor if the circuit and engine check out

    With good wiring, correct torque, and no abnormal mechanical noise, install a new sensor and confirm normal timing advance on a loaded test drive.

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