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P codepowertrainMedium severity

P0333Knock Sensor 2 Circuit High Input (Bank 2)

The Bank 2 knock sensor circuit is reading above its maximum voltage threshold, typically from a short to voltage, an open circuit, or a failed sensor.

Definition

P0333 is the Bank 2 counterpart to P0328 and sets when the knock sensor input exceeds the calibrated high limit — caused by the signal wire contacting a powered circuit, an open circuit on a biased input, or a sensor producing an excessive or distorted output. As with other knock-circuit faults, the PCM stops trusting the sensor and runs retarded ignition timing, giving reduced power and fuel economy with the MIL on. A signal pegged high can also come from severe genuine engine noise, so mechanical condition should be verified before parts are replaced.

Common causes

  • Signal wire shorted to battery or reference voltage
  • Open circuit on a biased input reading pegged high
  • Failed Bank 2 knock sensor producing excessive output
  • Severe engine mechanical noise saturating the sensor
  • Corroded or damaged connector and shielded wiring
  • PCM input circuit fault (rare)

Common misdiagnoses

  • Sensor replaced when the harness is shorted to voltage
  • Sensor replaced when rod knock or piston slap is saturating a good sensor
  • Bank 1 sensor replaced due to bank misidentification
  • PCM replaced before wiring checks

Troubleshooting steps

  1. 1.Listen for genuine engine noise

    A loud bottom-end or valvetrain noise on Bank 2 can legitimately peg the sensor — diagnose the mechanical issue first if one is audible.

  2. 2.Measure the signal-circuit voltage

    Backprobe the Bank 2 knock input key-on: a steady reading at or near battery/reference voltage indicates a short to voltage or an open biased circuit rather than sensor output.

  3. 3.Check the harness for shorts and opens

    With PCM and sensor disconnected, verify no continuity between the signal wire and any powered circuit, and under 1 Ω end to end.

  4. 4.Inspect the connector and shield

    Look for corrosion bridging terminals and a broken shield drain; a floating shield lets ignition noise ride on the signal and can mimic a high input.

  5. 5.Tap-test and substitute the sensor

    If the wiring proves good, scope the sensor's response to light taps — a distorted or continuously high output means replace it, torqued to specification on a clean boss.

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