2007 Subaru Impreza Knock Sensor Repair in Tualatin, OR

I’ve never heard of a knock sensor before in my whole life. What is this knock sensor thingy?

A knock sensor’s function is easy to understand but not necessarily easy to understand why you would need it. The knock sensor detects if there is any knocking in the engine.

Why is that important?

The knock sensor really senses vibrations in the engine. You may be thinking that there are many vibrations in the engine and that is true. The knock sensor detects the vibrations and reports them to the engine’s computer. The computer takes that information and looks for vibrations over a certain threshold. The threshold is what would be considered abnormal vibration levels for the engine. If they are detected then the engine knock sensor sends a signal that an abnormal vibration or knock has been detected inside the engine.

The knock sensor is reporting all vibrations to my 2007 Subaru Impreza’s computer then?

Yes. It tells your vehicle’s computer about all vibrations that it detects. The computer then takes that information and compares it against what is considered normal for the engine. If anything falls outside of those ranges then the knock sensor sends a signal that will alert the driver that there was a problem. The reason for this is because the knock sensor will try to protect your vehicle from experiencing a complete engine failure.

I can still drive my Impreza if I have this problem, right? I mean, it’s just a sensor. What harm could it do to my vehicle?

It is true that it is just a sensor, however, without the ability to detect, correctly, what kind of bumps your engine is taking then your engine could get damaged very easily. You should not drive your vehicle if you have a knock sensor problem. Your vehicle could develop a complete engine failure which will not only be expensive but dangerous for you, your passengers, and anyone who is driving near you at the time of failure.

How do you figure out that my knock sensor is the problem with my 2007 Subaru?

The OBD codes are the first thing that is looked at when starting to diagnose this problem. If the codes are consistent then the technician or mechanic will look at the sensor and the wires to see what is happening. If that checks out then the knock sensor has to be tested. They will benchmark the tests for comparison later. They will replace the knock sensor and see if that resolved the problem.

What are the codes you will be looking out for?

The OBD codes that your Impreza may give if you have this problem are the following codes:

  • P0324: Knock Control System Error
  • P0325: Knock Sensor 1 Circuit
  • P0328: Knock Sensor 1 Circuit High

Alright, well, how soon should I be worried about this thing going bad in my car?

Fortunately, most of these will last 150,000 miles or more barring mitigating circumstances.

What happens to my Subaru Impreza if I do have a bad knock sensor?

The engine’s computer will take steps as if you have vibrations that are consistent with problems. It will try to reduce your power output and it will show your check engine light. There are models of vehicles that will not allow you to restart your engine until the knock sensor has been fixed.

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