Code P0325: How To Fix It

Codes are complicated and it’s easy to get them mixed up in our heads. Unless you’re an expert mechanic then you might need a little bit of help when a new code pops up from time to time. There’s nothing wrong with that and it’s the reason we are putting these pieces together. So beginners and hobbyists can learn at their own pace. 

Today we are going to chat about a code that doesn’t take much to indicate but can require an expert when it comes to making repairs. If you aren’t familiar with knock sensors, get ready to learn because they are the main player in this game of whodunnit. 

Code P0325

When you see this code on your diagnostic tool it means that there is a knock sensor malfunction, specifically within knock sensor 1 inside circuit bank 1. It’s a general on-board diagnostics trouble code and it is commonly paired with other knock sensors and lean condition codes, which means your engine isn’t getting enough gas to the engine. 

What Are Knock Sensors?

Car knock sensors in a white background.

Their sole purpose of knock sensors is exactly what their name alludes to. They are there to listen for any “knocks” or strange expulsions of gas/air, which is caused by uneven combustion.

With a faulty knock sensor, your car will have certain issues, which we will discuss in a minute. Besides reading a code P0325, here are other ways to know there is a problem with your knock sensors. 

  • You might senseless power in your engine
  • The check engine light will come on

Other than these two indicators there are no other driving symptoms that would indicate an engine has a P0325 issue, which makes it a bit more insidious and worrisome. 

Is It Important?

Check engine light. Car dashboard in closeup

As we’ve said in the past, whenever the check engine light comes on it is important. But, we realize, when it comes to an engine, there are levels of importance, which could be said about many things in life. 

P0325 isn’t typically severe and you should be able to drive it to a mechanic, but we don’t recommend leaving it unattended for too long otherwise your engine might suffer some serious damage. 

Getting To The Root Of It

There are several reasons why you might be getting a P0325 code on your diagnostics tool. Some of them are as follows. 

Cropped view auto mechanic with mud on hands fixing automobile in car repair station
  • The ECU could’ve failed
  • The knock sensor may have malfunctioned
  • The wiring harness may have been open or there was a short
  • There could be issues with the electrical connections
  • The engine could be running leaner than usual
  • The could be a fault with the engine coolant system

How to Find The Problem

Now that we have an idea of what might be causing this error code here is how you can do some investigating to find out what the core of the issue is. 

Step One

Man inspection holding Battery Capacity Tester Voltmeter.for service maintenance of industrial to engine repair.In Factory transport automobile automotive image

The first thing we always suggest is to check the code again. We don’t think you didn’t read the code right the first time but it’s a good idea to make sure no other error codes are coming up so those can be taken care of. Once you have cleared out any other error codes then we can go to the next step. 

Step Two

Be sure to take down the freeze frame data for every code that comes up so you know the circumstances surrounding the engine like the RPM, run time, the speed you were going, and the coolant temp. 

Step Three

Clear the codes of all the data. 

Step Four

Driving car during low visibility at night

Take the car on a test drive. Your goal is to get the Check Engine Light to come on for confirmation.

Step Five

Now check for the right knock sensor operation by using a scan tool. Do this when revving the engine. 

Step Six

Check the knock sensor resistance. 

Step Seven

Take a look at the knock sensor wiring and their connections. You want to be sure there is no tearing or indications of disconnection. 

How To Fix It

Depending on what you uncover while conducting your investigation there are several ways you can make your repairs. 

  • Repair or replace the wiring harness
  • Replacing a damaged knock sensor
  • Fixing an electrical connection
  • Replacing the ECU

It is recommended that you replace the knock harness when you replace the sensor for better results. 

The Cost Of Repair

There isn’t much difference with this issue than any other problem you might find with a car or anything else. The cost of fixing it depends solely on parts and labor. The more you need to fix the more it will cost. This is why we work on our own cars when we can. But we always recommend using a professional for difficult jobs. 

Just One More Thing

Professional car repair or maintenance mechanic engine working service with laptop computer at workshop

Scan tools are great for diagnostics and pinpointing issues but the live data stream is perfect for this type of issue. It allows for greater accuracy and speed. 


When you see a P0325 code you now know that there is an issue with knock sensor 1 inside circuit bank 1. The ECU detects this problem when the information it gets from the knock sensor is not correct. This is what makes the check engine light start to glow on your dashboard.

That glowing engine could mean a myriad of things, which is why we have diagnostic tools. With all the codes out there our goal is to make your research surrounding it is clear cut and easy to follow. 

We hope you enjoyed this post. Let us know your thoughts in the comments section below and share this with your other car-loving friends.

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