Safe to drive. Repair to restore power and knock protection. P0328 means the Bank 1 knock sensor circuit read too high a voltage (or open). It is almost always a sensor, wiring, or connector fault rather than actual engine knock, and it makes the ECM run more conservative ignition timing.
What P0328 means
A knock sensor is a piezoelectric device bolted to the engine that detects the vibration of detonation so the ECM can retard timing to protect the engine. P0328 sets when the Bank 1 sensor's signal circuit reads above the expected range. Because the sensor is torque-sensitive and often buried under the intake, corrosion, mounting torque, and wiring are the usual culprits. With an unreliable knock signal, the ECM defaults to conservative timing, costing a little power and economy.
Symptoms
- Check engine light on
- Slightly reduced power and acceleration
- Small drop in fuel economy
- Possible pinging or knock under load if timing protection is compromised
- Often no obvious change in how the car drives
Common causes
- Failed knock sensor
- Loose or under-torqued sensor (correct torque is required for an accurate reading)
- Corroded or damaged connector at the sensor
- Wiring open or shorted to voltage on the signal circuit
- Rarely, an ECM fault
Severity & driving advice
Severity: Low-Moderate — Not an immediate breakdown risk, but the unreliable knock signal costs a little power and weakens detonation protection, so repair it.
Can I drive? Safe to drive. Repair to restore power and knock protection.
Diagnostic approach
- Inspect the sensor connector and wiring — Look for corrosion, chafing, or a short to power on the knock sensor circuit, which drives the voltage high.
- Measure the knock sensor — Compare the sensor's resistance to specification; a piezo knock sensor out of range should be replaced.
- Confirm correct mounting torque — A knock sensor that isn't torqued to spec against the block reads inaccurately, so verify and correct the torque.
- Back-probe the signal circuit — Check the signal at the ECM side to isolate whether the fault is the sensor or the harness.
- Rule out real detonation — Confirm there isn't genuine heavy knock from carbon, timing, or fuel issues before replacing the sensor.
- Replace the sensor if out of spec — If wiring and torque are good and the sensor is out of range, replace it — on V engines this can be labor-heavy under the intake.
Make & model notes
Toyota / GM: On many V6 engines the knock sensors sit in the valley under the intake manifold, so replacement is labor-intensive; use the correct torque or the new sensor will read inaccurately.
General: A short to voltage in the harness, not the sensor itself, is a common reason the circuit reads high — always check wiring before condemning the sensor.
FAQ
Can I drive with P0328?
Yes. The car will run, though with slightly reduced power and less knock protection. Repair it before hard driving or towing.
Is P0328 real engine knock?
Usually not — it's a circuit reading too high, pointing to the sensor or wiring. Still, rule out genuine detonation before replacing parts.
Why is the knock sensor so hard to reach?
On V6/V8 engines the sensors often mount in the engine valley beneath the intake manifold, which has to come off for access.
Will a bad knock sensor hurt my engine?
Indirectly — without a reliable knock signal the ECM can't retard timing as precisely, so persistent detonation could eventually cause damage.