P0325 – Knock sensor 1 circuit

The P0325 code relates to the knock sensor on the bank 1 side of your car’s engine. It basically tells you it isn’t sending the right signals to the computer. There are a lot of reasons this could be happening, from bad wiring to a faulty sensor.

P0325 is a generic powertrain code that applies to a wide range of vehicle types. Having said that, it’s seen more often on certain cars than others. It’s more common in Asian cars than those made in the United States or Europe and is most common on Hondas, Nissans, and Toyotas.

You won’t likely experience any drivability issues when the P0325 code is active, but that doesn’t mean you can ignore it. Read on below to learn how to diagnose and repair this knock sensor trouble code before it leads to further problems.

P0325 code definition

P0325 code definition (generic): Knock sensor circuit malfunction (bank 1)

P0325 Honda code definition: Knock sensor circuit malfunction

P0325 Hyundai code definition: Knock sensor circuit malfunction

P0325 Nissan code definition: Knock sensor circuit malfunction

P0325 Toyota code definition: Knock sensor circuit malfunction

Here's where you can get a thorough understanding of the P0325 OBD2 code
If you want to learn about the P0325 OBD2 code, this is the right place

What does P0325 mean?

The knock sensor in your engine is there to tell you when the air/fuel mixture isn’t combusting properly. It detects explosions, which are called knocks, because of the noise they cause. When knocks happen, the engine doesn’t get as much power. If these happen for too long, it can cause engine damage.

The information sent to the computer from the knock sensor allows it to make adjustments. It may change the timing or otherwise tune the engine to prevent the knocks. You’ll find the knock sensor bolted or threaded into the engine block.

When the engine computer isn’t receiving the right information from the knock sensor, it triggers the P0325 trouble code. This code specifically refers to the knock sensor on bank 1 of the engine. Bank 1 is the side that includes cylinder 1.

What are the symptoms of the P0325 code?

There are not typically any drivability symptoms with the P0325 trouble code. The most common symptoms are:

If there are engine knocks occurring as well as damage to the knock sensor, you may notice the following symptoms:

  • Hesitation from the engine
  • Audible pinging from the engine, especially while accelerating
  • Reduced fuel economy

What are the causes of P0325?

  • Faulty knock sensor,
  • Shorted or faulty wiring in the knock sensor circuit,
  • Shorts or faults in the wiring harness,
  • Faulty or loose electrical connections,
  • Faults with engine coolant system,
  • Engine running too lean,
  • Failed PCM or ECU.

How serious is the P0325 code?

The P0325 trouble code is of relatively low severity. You won’t notice any drivability symptoms in most cases and can drive your car safely until you can repair it. However, it would be best if you fixed it quickly so you can be notified of knocking problems, which can damage your engine.

How to diagnose the P0325 code

Tools you’ll need:

The P0325 code can be diagnosed with an OBD2 scan tool
An OBD2 scan tool can be used to diagnose the P0325 code


  1. Check your vehicle’s manual for any specific troubleshooting tips related to the knock sensor. You can also check if there are any technical service bulletins out related to this trouble code. The repair for P0325 is often vehicle-specific. Follow any manufacturer-specific instructions you find before proceeding with the generic diagnostic below.
  2. Use your OBD2 scanner to check for any other codes. You may see other codes related to the knock sensor, such as P0330. If you see codes related to other sensors, such as the MAF sensor or oxygen sensors, this likely points to a wiring problem.
  3. Read the freeze frame data related to the knock sensor. Check the conditions that were present when the code was set, which can help you make a complete diagnosis.
  4. Clear the codes and test drive your vehicle, attempting to replicate the conditions of the failure.
  5. Verify that the knock sensor is sending a signal to the powertrain control module. If it’s not, use the OBD2 scanner to check the readings from the coolant temperature sensor.
  6. Visually inspect the wires around the knock sensor and wiring harness. Replace any wires that are damaged or corroded and ensure all the connections are secure.

Common mistakes to avoid while diagnosing the P0325 code

Many people replace the knock sensor before checking the wiring or looking for issues with the coolant system. Make sure you conduct a thorough diagnosis before replacing any components.

What should you do to fix the code P0325?

After each step of your repairs, clear all the trouble codes and test drive your vehicle to see if the code comes back. Since there are rarely drivability issues with this code, your OBD2 scanner will be crucial in discovering if you’ve fixed the problem.

  1. Replace any damaged wires you found during your diagnosis.
  2. If you detected any issues with the coolant temperature readings, replace the temperature sensor. Incorrect temperature readings can lead to overheating and other serious engine issues.
  3. If you’re certain there are no damaged wires or missing connections in your engine, replace the knock sensor and the knock harness.
  4. Should the P0325 code still not clear, take your car to a mechanic for further diagnosis. In rare instances, this code could indicate a problem with your electrical connections or the engine computer.

Tips to avoid P0325 in the future

How to diagnose and fix the P0325 code

An improperly-installed knock sensor is the most common cause of a P0325 code. Wires that aren’t firmly connected could be shaken loose over time by the vibration of the engine. Damaged or broken wires will also often trigger diagnostic trouble codes—not only P0325 but a host of codes related to sensors throughout your engine.

Take the extra time to check all the wires whenever you install or repair something in your engine. Check that the connections are secure and that the wires are clear of things that could cause damage or shorts.

Read more: P0010 Code: Meaning, Symptoms, Causes, Diagnostics, and Fixes