OBD-II Code P0328 — What It Means & How to Fix It

What Does This Error Mean?

P0328 means the knock sensor 1 signal voltage is higher than the expected range. The PCM is seeing a signal that is too strong — suggesting a wiring fault or a sensor sending a false knock signal. The engine may aggressively retard ignition timing based on the false signal. This leads to reduced power, hesitation, and worse fuel economy.

Affected Models

All 1996+ vehicles with knock sensors
Common in GM V8 engines with dual knock sensors
Common in Toyota and Lexus V6 and V8 engines
Common in Nissan and Infiniti V6 engines
Common in Ford and Lincoln V6 and V8 engines

Common Causes

Failed knock sensor sending a constant high-voltage or abnormally strong output
Short circuit to voltage (power wire contacting the signal wire) causing elevated signal
Corroded connector creating a false high-resistance or high-voltage condition
Engine mechanical noise (worn bearings, rod knock) generating excessive vibration
Incorrect knock sensor installed with wrong resistance or sensitivity characteristics

How to Fix It

Check for engine mechanical noise before suspecting the sensor. Listen for a ticking, knocking, or rattling sound at idle or under acceleration. Real engine knock can cause the knock sensor to produce a legitimately high signal — which is exactly what it is designed to do.

If you hear engine knocking or pinging, address the mechanical issue first. A knock sensor code caused by real engine knock means the sensor is working correctly.
Check the knock sensor connector and signal wire for a short to power. Unplug the sensor and check the signal wire terminal for voltage. There should be no voltage present on the signal wire with the sensor unplugged unless there is a wiring fault.

A short from a nearby power wire to the sensor signal wire will push the voltage high and cause P0328 even with a new sensor.
Inspect the knock sensor connector for corrosion or damage. Corroded pins can create unusual resistance values that the PCM interprets as a high-voltage condition. Clean the connector with electrical contact cleaner and reconnect firmly.

Corrosion is especially common in engines where the sensor is buried under the intake manifold in a humid or oil-misted environment.
Verify you have the correct knock sensor part number installed. Using a sensor with different resistance or sensitivity specifications than the OEM part can cause either high or low input codes. An aftermarket sensor that does not meet spec will not solve the problem.

Stick with OEM or OEM-equivalent quality sensors for knock sensors. Cheap sensors often have incorrect output characteristics.
Replace the knock sensor if electrical tests confirm the sensor itself is faulty. Torque it to the manufacturer's specification — typically 15-20 Nm. Clear stored codes and drive through several heat cycles to confirm the repair is successful.

After replacing a knock sensor, the PCM may take a few drive cycles to fully restore timing advance. Full power restoration may not be immediate.

When to Call a Professional

If cleaning the connector and replacing the sensor does not resolve P0328, a wiring short or engine mechanical noise may be at fault. A technician can check for an open or short in the signal circuit and listen for mechanical knock with a stethoscope. Diagnosis typically costs $80-$130. Knock sensor replacement runs $100-$300 depending on access and vehicle.

Frequently Asked Questions

Could real engine knock cause P0328?

Yes, absolutely. If your engine is genuinely knocking or pinging, the knock sensor will produce a high-output signal. The PCM then retards timing, which should stop the knock. If the knock is severe or mechanical in origin, the code will keep returning. Do not ignore P0328 if you also hear engine noise.

Will P0328 damage my engine?

Not directly. But the PCM responds by aggressively retarding ignition timing. This significantly reduces power and fuel economy. If real engine knock is the cause, the underlying knock will damage the engine if not addressed. Fix the root cause — whether it is the sensor or real mechanical knock.

Is P0328 the opposite of P0327?

In a sense, yes. P0327 means the knock sensor signal is too low. P0328 means the signal is too high. Both indicate the sensor circuit is outside the normal operating range. The diagnostic approach differs — P0327 looks for shorts to ground; P0328 looks for shorts to power or actual engine noise.