Engine

P0334 — Knock Sensor 2 Circuit High Input (Bank 2)

Severity: medium Drive with care, to a shop

What P0334 means

A knock sensor is a piezoelectric device that listens for engine vibration caused by detonation. The ECM uses its signal to retard ignition timing when needed to protect the engine. P0334 is set when the voltage in the Bank 2 knock sensor 2 circuit is higher than expected. The cause can be the sensor, its wiring or connector, or, less often, the ECM.

Symptoms

  • Check engine light is on
  • Reduced power and sluggish throttle response
  • Intermittent hesitation or stumble
  • Worse fuel economy
  • Audible pinging or knocking under load
  • Rough idle

Possible causes

  1. Failed Bank 2 knock sensor
  2. Damaged wiring: open circuit, chafed insulation or short to voltage
  3. Corroded or loose connector terminals
  4. Poor or unstable sensor ground
  5. Fault in the ECM sensor input circuit (rare)
  6. Real engine mechanical noise mistaken for knock (rare)

How to diagnose

  1. Scan for all codes and review freeze frame data; look for other ignition or sensor faults.
  2. Inspect the Bank 2 knock sensor harness and connector for chafing, oil contamination, heat damage and corrosion.
  3. Confirm the sensor is installed and torqued to spec and sits flat against the block.
  4. Unplug the connector and check the signal and ground circuits with a multimeter per the factory wiring diagram.
  5. Test the circuit for a short to voltage and for an open between the sensor and the ECM.
  6. Check the sensor's resistance or output against factory specs; a scope while tapping the block near the sensor helps.
  7. If wiring and sensor are good, check the circuit at the ECM and only then consider ECM repair or replacement.

Common fixes

  • Replace the Bank 2 knock sensor
  • Repair or replace damaged wiring or the connector
  • Clean the terminals and restore a solid ground
  • Diagnose, repair or reflash the ECM if it is the cause

Questions and answers

What does P0334 mean?

The ECM detected a high voltage in the knock sensor 2 circuit on Bank 2. The sensor or its wiring is the most common cause.

Can I drive with P0334?

Briefly and gently, yes. The engine will run with reduced power and timing, and without proper knock protection heavy loads can damage it.

How do I fix P0334?

Start by checking the Bank 2 knock sensor wiring, connector and ground. If those are fine, replace the sensor, and look at the ECM last.

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.