Knock Sensor 1 Circuit Bank 1
The Powertrain Control Module (PCM) detected a malfunction in the electrical circuit of knock sensor 1 on bank 1. This code is set when the PCM does not receive the expected voltage signal from the knock sensor, indicating a circuit fault rather than actual engine knock.
While the vehicle can usually still be driven, the PCM will retard ignition timing to prevent potential engine damage from undetected knock. This reduces performance and fuel economy, so it should be diagnosed and repaired soon.
Common symptoms
- Illuminated Check Engine Light
- Noticeable lack of engine power or sluggish acceleration
- Decreased fuel economy
- Engine pinging or knocking sounds under load
- Hesitation or stumbling during acceleration
Likely causes
- Faulty knock sensor 1 (Bank 1)
- Damaged, corroded, or loose wiring or connector at the knock sensor
- Short or open circuit in the knock sensor wiring harness
- Incorrect knock sensor mounting torque (if recently replaced)
- Faulty Powertrain Control Module (PCM)
What to check before replacing parts
Visually inspect the knock sensor wiring and connector.
Look for: Look for frayed wires, melted insulation, corrosion in the connector pins, or a loose connection.
Measure the resistance of the knock sensor using a digital multimeter.
Look for: Compare the resistance reading to the manufacturer's specification; an open circuit (infinite resistance) or out-of-spec reading indicates a failed sensor.
Check for reference voltage at the knock sensor connector.
Look for: With the key on and engine off, verify the presence of the correct reference voltage (usually 5V) from the PCM to ensure the wiring harness is intact.
Test the wiring harness for continuity between the sensor connector and the PCM.
Look for: High resistance or no continuity indicates a break in the wire, while continuity to ground indicates a short circuit.
Verify the knock sensor mounting torque.
Look for: Ensure the sensor is tightened to the exact factory torque specification, as over-tightening or under-tightening can distort the signal.
This page explains the generic P0325 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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