Knock Sensor 1 Circuit Low (Bank 1 or Single Sensor)
The P0327 code means the vehicle's onboard diagnostic system has detected: Knock Sensor 1 Circuit Low (Bank 1 or Single Sensor). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $150 - $500 (parts and labor)
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Common Symptoms
- Check Engine Light illuminated
- Reduced engine power
- Engine pinging or knocking under acceleration
- Poor fuel economy
- Hesitation under load
Probable Causes (Ranked by Likelihood)
- Faulty knock sensor 1 producing weak signal Very High
- Short to ground in knock sensor wiring High
- Corroded or loose knock sensor connector High
- Knock sensor installed with incorrect torque Moderate
- PCM input circuit issue Low
Step-by-Step Diagnostic Procedure
-
Measure knock sensor output voltage while tapping the engine block near the sensor -- should produce measurable voltage spikes
-
Check for shorts to ground in the sensor wiring with a multimeter -- disconnect sensor and test signal wire to ground
-
Inspect the sensor connector for corrosion, oil contamination, or pushed-back pins
-
Verify the sensor is torqued to specification -- an undertorqued sensor produces weak signals
-
Replace the knock sensor if output is consistently below the expected threshold
Common Fixes by Vehicle
What techs usually find when diagnosing P0327 on specific vehicles — tap your vehicle for the fix and the exact part:
2007-2020 Chevrolet Silverado/GMC Sierra 5.3L Moderate DIY
Bank 1 knock sensor low input. The knock sensors on the 5.3L are located under the intake manifold in the lifter valley. ACDelco 213-3521. These fail from oil contamination and heat. The intake manifold must be removed for access. Torque the new sensor to exactly 15 ft-lbs. GM TSB #16-NA-175 covers knock sensor diagnosis.
Labor: 3-4 hours2002-2015 Nissan Altima/Maxima 2.5L/3.5L Moderate DIY
Knock sensor under the intake manifold has failed or the wiring harness is damaged. Nissan TSB NTB04-018. Remove the intake manifold and replace the sensor (Hitachi KNS0025). While the manifold is off, check for coolant leaking from the upper intake coolant crossover onto the sensor connector. Clean and reseal the coolant passage.
Labor: 2-3 hours2007-2017 Toyota Camry/RAV4 2.5L Moderate DIY
Knock sensor below the intake manifold has low output. Replace with Denso 89615-06010. The intake manifold must be removed for access -- a 2-3 hour job. While the manifold is off, replace the intake gaskets and inspect the coolant crossover pipe for leaks. Over-torquing the new sensor will cause false readings -- torque to 20 ft-lbs per Toyota spec.
Labor: 2-3 hoursFrequently Asked Questions
Can I drive with code P0327?
You can drive short distances. The PCM will retard timing, reducing power. If the engine is actually knocking due to bad fuel or carbon buildup, driving under load could cause piston or bearing damage.
Can low-quality fuel trigger a knock sensor code?
Low-quality fuel can cause actual engine knock, but the knock sensor code itself indicates a sensor circuit problem. If the sensor were working correctly, it would detect the knock and the PCM would retard timing without setting a sensor code.
Is the knock sensor hard to replace?
The difficulty depends on the vehicle. On many engines, the knock sensor is under the intake manifold, requiring its removal. This adds significant labor time to what is otherwise a simple sensor swap.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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