Knock Sensor 1 Circuit High (Bank 1 or Single Sensor)
The P0328 code means the vehicle's onboard diagnostic system has detected: Knock Sensor 1 Circuit High (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
- Excessive ignition timing retard
- Significant power loss
- Poor fuel economy
- Engine may feel sluggish
Probable Causes (Ranked by Likelihood)
- Knock sensor overtightened or damaged Very High
- Engine mechanical noise generating false knock signals High
- Short to voltage in knock sensor signal wiring High
- Faulty knock sensor producing excessive output Moderate
- PCM incorrectly interpreting normal engine noise as knock Low
Step-by-Step Diagnostic Procedure
-
Check knock sensor torque -- overtightening is a common cause of high signal output
-
Listen for abnormal engine noises such as rod knock, piston slap, or exhaust leak that could trigger false knock signals
-
Check for short to voltage in the knock sensor signal wire
-
Monitor knock sensor voltage with a scan tool at idle -- excessively high readings indicate sensor or noise issues
-
Replace the knock sensor and torque to exact specification if electrical tests point to sensor failure
Common Fixes by Vehicle
What techs usually find when diagnosing P0328 on specific vehicles — tap your vehicle for the fix and the exact part:
1999-2014 GM 4.8/5.3/6.0L V8 moderate DIY
Knock sensor 1 circuit high on bank 1 is a classic GM truck code — the knock sensors sit in the valley under the intake manifold and their connectors corrode from water intrusion. Replace both knock sensors and the wiring harness with a sealed kit while the intake is off. Use dielectric grease on the new connectors.
Labor: 2-4 hoursFrequently Asked Questions
Can I drive with code P0328?
You can drive short distances, but the PCM will heavily retard ignition timing causing noticeable power loss and poor fuel economy. Have it diagnosed to rule out actual engine knock.
Can a loose exhaust manifold bolt cause P0328?
Yes. An exhaust leak near the engine block creates a ticking or knocking noise that the knock sensor can misinterpret as engine detonation, causing a high signal reading.
What happens if the knock sensor signal is always high?
The PCM will constantly retard ignition timing to protect the engine from perceived knock. This causes significant power loss and poor fuel economy but does prevent potential engine damage.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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