Knock sensor codes

How its codes differ

• P0325 is the circuit code for knock sensor 1 (bank 1, or the only sensor): the computer has found a fault in the sensor's circuit, pointing to the sensor, its connector or wiring. Honda has a bulletin for P0325 caused by rodents chewing the knock sensor harness.
• P0332 is a low-signal code for knock sensor 2 (bank 2): often an open or shorted circuit, a loose or corroded connection, or a sensor that is not mounted correctly.
• Real knock can also be the problem rather than the sensor: low-octane fuel, carbon build-up, a lean mixture or overheating can all cause detonation, so a knock code with audible pinging needs both checked.
• While knock detection is not working, the computer may use more cautious ignition timing, which is why power and fuel economy can drop.

Codes

• P0325

  Knock sensor 1 circuit fault (bank 1 or single sensor)

  Severity: Inspect soon

• P0332

  Knock sensor 2 circuit voltage low (bank 2)

  Severity: Inspect soon

Signs it's failing

• Check engine light with P0325 or P0332
• Pinging or knocking on acceleration
• Weaker acceleration or less power
• Worse fuel economy

How to test it

1. Read all stored codes and fix any lean, overheating or misfire codes first, since they can cause real knock. (Low risk)

2. Make sure you are using the fuel octane the owner's manual calls for. (Low risk)

3. With the engine off, check the knock sensor connector and any visible wiring for corrosion, looseness or rodent damage. (Low risk)

4. Testing the sensor signal (for example with an oscilloscope) and replacing the sensor are shop jobs. (Best left to a shop)

   Warning: Installation affects the reading: a sensor fitted at the wrong torque or the wrong way up can set the code again. Have a technician fit it to the vehicle's specification.

After the repair

• Clear the code and confirm it does not return after a drive that includes acceleration under load.
• Listen for pinging under load; if it continues, the cause may be real detonation rather than the sensor.
• Clear codes only after the repair, then drive normally over several days with both city and highway driving so the readiness monitors can complete; clearing codes or disconnecting the battery resets them to not ready, which fails an emissions test.