Knock Sensor 1 Circuit High (Bank 1 or Single Sensor)
The Powertrain Control Module (PCM) has detected an abnormally high voltage signal from the knock sensor on Bank 1. This indicates the sensor circuit is likely shorted to voltage or the sensor itself is internally shorted, preventing the PCM from accurately detecting engine detonation.
While the vehicle will usually still drive, the PCM may retard ignition timing to protect the engine from potential detonation. This can lead to reduced power and poor fuel economy, so it should be diagnosed soon to prevent long-term engine stress.
Common symptoms
- Illuminated Check Engine Light
- Noticeable lack of engine power or sluggish acceleration
- Decreased fuel efficiency
- Engine pinging or knocking sounds under heavy load
- Hesitation or stumbling during acceleration
Likely causes
- Faulty knock sensor (Bank 1)
- Short to voltage in the knock sensor wiring harness
- Corroded, damaged, or loose knock sensor connector
- Incorrectly torqued knock sensor (if recently replaced)
- Internal engine mechanical issue causing severe knocking
- Faulty Powertrain Control Module (PCM)
What to check before replacing parts
Inspect the knock sensor wiring and connector.
Look for: Look for chafed wires, melted insulation, or corrosion in the connector that could cause a short to voltage.
Check the knock sensor circuit voltage with a multimeter.
Look for: Disconnect the sensor and measure the reference voltage from the PCM. If it reads battery voltage instead of the expected 5V reference (on most systems), there is a short to power in the harness.
Test the knock sensor resistance.
Look for: Measure the resistance across the knock sensor terminals. If it reads out of the manufacturer's specified range or shows an internal short, the sensor is faulty and requires replacement.
Verify the knock sensor torque.
Look for: Ensure the sensor is tightened to the exact factory torque specification. An over-tightened sensor can crush the internal piezoelectric crystal and produce an artificially high voltage signal.
Monitor knock sensor data via a scan tool.
Look for: Observe the knock sensor voltage while lightly tapping the engine block near the sensor with a wrench. The signal should spike and return to baseline; a constant high reading confirms a circuit or sensor failure.
This page explains the generic P0328 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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