Engine

P033D — Knock Sensor 4 Circuit High (Bank 2)

Severity: medium Drive with care, to a shop

What P033D means

The knock sensor listens for engine block vibration so the ECU can pull back ignition timing when detonation occurs. P033D is set when the voltage in the circuit of knock sensor 4 on bank 2 is higher than expected. It is usually caused by a wiring fault, a poor connection or a failed sensor.

Symptoms

  • Check engine light on
  • Reduced power or hesitation
  • Rough idle
  • Possible pinging or knocking under acceleration
  • Higher fuel consumption

Possible causes

  1. Failed knock sensor 4 on bank 2
  2. Damaged, corroded or chafed wiring and connectors in the sensor circuit
  3. Poor connection at the sensor or ECU connector
  4. Open signal wire or short to voltage
  5. ECU input circuit fault (rare)
  6. Real knock from low-octane fuel (rare)

How to diagnose

  1. Scan all codes and freeze frame data, and note any other knock sensor codes
  2. Inspect the harness and connector for oil, corrosion, chafing and heat damage
  3. Identify the bank 2 sensor 4 location from the wiring diagram and check the mounting torque
  4. Unplug the connector and test sensor resistance and reference voltage against specs
  5. Test the signal wire for an open or a short to power or ground
  6. Check ground quality and the ECU connector pins
  7. Compare live data with expected values and make sure real knock is not present
  8. Clear the code and road test after repair

Common fixes

  • Replace the knock sensor and torque it to spec
  • Repair or replace the damaged harness or connector
  • Clean and secure the electrical connections
  • Repair or replace the ECU if confirmed faulty (rare)

Questions and answers

What does P033D mean?

It means the voltage in the knock sensor 4 circuit on bank 2 is too high. The usual culprits are the sensor, its wiring or a bad connection.

Can I drive with P033D?

For a short time, yes, but the engine will likely run in a protective mode with less power. Extended driving under load risks engine damage, so do not put off diagnosis.

Is replacing the knock sensor enough?

Not always. Check the wiring and connector first, since they are often the real problem and a new sensor will not fix them.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.