What is a knock sensor circuit malfunction?

P0325 code definition

Knock Sensor Malfunction (Sensor 1, Bank 1)

What the P0325 code means

P0325 is a general ODB2 diagnostic trouble code associated with the knock sensor circuit. This code may be seen with other knock sensor codes and lean condition codes.

P0325 means that there is a malfunction within the knock sensor 1 in circuit bank 1. This malfunction will be detected by the ECU when it does not receive the proper information from the knock sensor. This triggers a Check Engine Light to be illuminated on the dashboard.

What causes the P0325 code?

A failed ECU
A failed knock sensor
Open or short in the wiring harness
Electrical connection issues

What are the symptoms of the P0325 code?

The Check Engine Light illuminating on is normally the most noticeable symptom.
The engine may have a slight lack of power.
There may be no felt symptoms with P0325.

How does a mechanic diagnose the P0325 code?

Uses a scan tool to check for any codes, there may be history, pending and current codes
Notes the freeze frame data for each of these codes this will show the conditions the vehicle was under when the code was set such as engine RPM, coolant temp, run time, and vehicle speed
Clears the code to have a fresh start to diagnosis
Performs a road test to try to get the Check Engine Light to come back on and confirm the issue is present
Uses a scan tool to check for proper knock sensor operation while the engine is revved
Checks the resistance of the knock sensor
Tests the ECU test following the manufacturer's testing procedures if needed.

Common mistakes when diagnosing the P0325 code

With any code, even the most experienced technician can make simple mistakes and overlook the basics if they do not follow all of the diagnostic steps or do not complete them in order.

How serious is the P0325 code?

P0325 is generally not a serious code and should be able to be driven without issue to a safe location once the malfunction occurs. Some vehicles may experience a slight lack of engine power as the ECU will retard timing to prevent damage in case the engine was knocking.

What repairs can fix the P0325 code?

Replacing the ECU
Repairing or replacing the wiring harness
Replacing a faulty knock sensor
Repairing an electrical connection

A scan tool that does more than just check codes will be needed for performing accurate diagnosis of P0325. Many of the items that are checked can be done much faster and more accurately with the live data stream these scan tools allow access to.

Need help with a P0325 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light

P0325

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What Does Code P0325 Mean?

P0325 definition: Knock Sensor 1 Circuit Malfunction (Bank 1)
Issue Severity: LOW – Continued driving for a short period of time is okay
Repair Urgency: Get this fixed within the next month to prevent damage to your engine and emission system.
Diagnosis: There are no driveability concerns with trouble code P0325. However, along with all Diagnostic Trouble Codes, there should be a sense of haste in getting this repaired so that there is no further damage to the engine.

Knock sensors are solely used for the purpose of sensing when your engine is “knocking,” or sensing when the air/fuel mixture combusts prematurely. This delivers less power and can also damage the engine if prolonged. When the engine “knocks” there is also an excessive amount of NOx that is released. When trouble code P0325 is set, this means that knock sensor 1 in bank 1 is not operating properly.

P0325 Causes

There are many potential causes of code P0325.

Engine is running excessively lean
Faulty or damaged knock sensor wiring
Faulty sensor 1 Bank 1 knock sensor
Engine coolant system fault

P0325 Symptoms

Check Engine Light
Loss of engine power
No noticeable drivability issues

How Do I Fix Code P0325?

With a knock sensor fault, the first step is to get it diagnosed to figure out what is causing the problem.

If your vehicle has this fault and you’re not comfortable diagnosing this issue at home, we recommend finding a RepairPal certified shop nearby to pinpoint the problem and give an accurate estimate for repairs.

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

> Find a RepairPal Certified Shop Near You

How Much Does It Cost to Fix Code P0325?

P0325 can be caused by anything from damaged wiring to a bad knock sensor to an overheating engine. It’s impossible to give an accurate estimate without properly diagnosing the issue first.

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0325 code.

Possible Repair Costs for P0325

For error code P0325, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.

Knock sensor: $297 to $381
Knock sensor harness: $14 to $66
Temperature sensor: $392 to $427

DIY Steps to Diagnose Code P0325

Engine code P0325 could be caused by a number of things, including damaged wiring, a bad knock sensor, or an overheating engine. If you’d like to try to fix code P0325 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Keep in mind this is an intermediate-level diagnosis and repair and not recommended for beginners. Diagnosis requires more specialized equipment beyond what the FIXD Sensor can provide and it can be a time and labor-intensive process for inexperienced DIYers.

DIY difficulty level: Intermediate

This repair requires mechanical knowledge and is not recommended for beginners.

Tools/parts needed (our top picks from Amazon):

FIXD
Live Data (Found on FIXD App with Sensor)

STEP 1: USE FIXD TO ENSURE NO OTHER ENGINE CODES ARE PRESENT.

Use FIXD to scan your vehicle to verify P0325 is the only code present. If not, make a note of the additional codes, as they help diagnose the problem.

STEP 2: CLEAR CODES, DO A ROAD TEST.

Clear the fault codes with your FIXD sensor, then go for a drive to see if the problem comes back. Include some uphills and hard acceleration, which are both conditions that would cause engine knock. If the Check Engine Light comes back on, scan the codes again to see if they are the same or different than the first time.

STEP 3: CHECK KNOCK SENSOR SIGNAL.

Using FIXD Live Data, check the knock sensor voltage to ensure that it is within the specified range. If it is not, or if there is no signal at all, skip to Step 5.

STEP 4: CHECK TEMPERATURE SENSOR SIGNAL.

Using FIXD Live Data, check the temperature sensor voltage to ensure that it is within the specified range. If it is not, the temperature sensor may be sending false readings to the PCM, which could cause a lean running condition and engine knock. Check the temperature sensor and wiring and replace if necessary.

STEP 5: INSPECT KNOCK SENSOR WIRING.

Visually inspect the wiring around the knock sensor for disconnected or damaged wires.

STEP 6: REPLACE KNOCK SENSOR AND HARNESS.

If the conclusion is that the knock sensor needs to be replaced, then it is often recommended to replace not only the sensor but the knock harness as well.

Common P0325 diagnosis mistakes

There are times when the engine coolant system is the issue and replacing the knock sensor immediately will not make the Check Engine Light turn off.

Still Need Help Fixing Code P0325?

If you’ve followed the steps above and are still experiencing check engine code P0325, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.

Can you drive with a knock sensor malfunction?

In conclusion, you can drive with a bad knock sensor—that is, if you want to destroy your engine and get atrocious performance from your car. The moment you confirm that your knock sensor has seen better days, it would be wise to swap it right away with a high-quality replacement.

What happens when the knock sensor goes bad?

The knock sensor senses the vibrations of the engine and will decrease acceleration until the sensor is replaced. With a faulty sensor, there is a chance that higher emissions are being produced from the engine because the engine may run hot.

What causes a knock sensor to malfunction?

Ankylosing spondylitis has no known specific cause, though genetic factors seem to be involved. In particular, people who have a gene called HLA-B27 are at a greatly increased risk of developing ankylosing spondylitis. However, only some people with the gene develop the condition.