Knock Sensor 1 Circuit Malfunction (Bank 1)
The P0325 code means the vehicle's onboard diagnostic system has detected: Knock Sensor 1 Circuit Malfunction (Bank 1). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- medium
- Estimated cost
- $30-$80 for the knock sensor part; roughly $300-$700 on a Nissan V6 because the intake plenum, lower runners, and fuel rail must be removed (the sensor sub-harness is usually replaced too)
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Common Symptoms
- Check Engine Light on
- Possible engine knock or pinging under load
- Reduced ignition timing advance (protective ECU response)
- Slight power reduction
Probable Causes (Ranked by Likelihood)
- Failed knock sensor Very High
- Damaged or corroded wiring/connector to knock sensor High
- Knock sensor mounting issue (loose, improper torque) Moderate
Step-by-Step Diagnostic Procedure
-
Inspect the knock sensor wiring harness and connector for corrosion, cuts, or heat damage.
-
Test knock sensor resistance, but the value is highly sensor-dependent and must come from your service manual. Flat-response (2-wire) sensors often read about 90-150k ohms, while many high-impedance Nissan/resonant sensors spec roughly 500-625k ohms. A reading that looks wrong against a generic number is meaningless without the OEM spec for your exact engine.
-
Verify torque on the knock sensor: over-tightening causes incorrect readings, under-tightening causes P0325.
-
On Nissan vehicles (common problem), inspect for coolant intrusion into the knock sensor harness connector under the intake manifold.
Common Fixes by Vehicle
What techs usually find when diagnosing P0325 on specific vehicles — tap your vehicle for the fix and the exact part:
2007-2017 Toyota Camry/RAV4 2.5L moderate DIY
Knock sensor is located under the intake manifold on the 2AR-FE engine. Toyota knock sensors fail from heat and vibration. Replace with Denso 89615-06010. This is a 2-3 hour job because the intake manifold must be removed. While the manifold is off, replace the intake gaskets and check for coolant crossover pipe leaks.
Labor: 2-3 hours2002-2015 Nissan Altima/Maxima 2.5L/3.5L moderate DIY
Knock sensor is buried under the intake manifold. Nissan TSB NTB04-018 covers this. The sensor (Hitachi KNS0025) corrodes from coolant leaks. While the intake manifold is off, check for coolant in the sensor connector -- the upper intake coolant passage leaks onto the wiring. Replace the sensor, clean the connector, and reseal the coolant passage.
Labor: 2-3 hours2010-2020 Chevrolet Silverado/Tahoe 5.3L hard DIY
GM V8 knock sensors are under the intake manifold in the lifter valley. ACDelco 213-3521. Commonly fail from AFM oil splashing on the sensors. While the intake is off, inspect the AFM lifters if equipped. GM TSB #16-NA-175 covers knock sensor diagnosis. Torque the sensor to exactly 15 ft-lbs -- over-torquing causes false knock readings.
Labor: 3-4 hours2008-2019 Honda Accord/CR-V 2.4L moderate DIY
The knock sensor on the K24 is located on the engine block below the intake manifold. Easier access than most engines -- remove the air intake and a heat shield. Replace with Denso 30530-PNA-003. If the code is intermittent, check the wiring harness for chafing against the engine block. Apply thread sealant to the new sensor since the port is near the coolant jacket.
Labor: 1-1.5 hoursFrequently Asked Questions
Is P0325 serious?
The sensor failure itself does not damage the engine, but the ECU will retard ignition timing as a precaution, reducing power and fuel economy. In the meantime, avoid using low-octane fuel and avoid heavy loads that could cause undetected knock.
Why is P0325 so common on Nissan?
The Nissan VQ35DE and KA24DE engines route the knock sensor harness under the intake manifold in an area prone to coolant exposure. The connector corrodes, causing the fault. The repair requires removing the intake manifold, which drives up cost.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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