P0328: Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor)

P0328 means the ECU is detecting a voltage on the knock sensor 1 signal that is higher than the expected range. This typically happens when the signal wire is shorted to a 12 V source, the sensor has failed internally, or the wiring is open in a way that leaves the input floating. Without a trusted knock signal the ECU adopts conservative timing, reducing performance and fuel economy.

P0328 is a ignition-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0328 and illuminates the check engine light.

If your vehicle has triggered P0328, you may notice one or more of these symptoms:

• Check engine light on
• Noticeable loss of power, especially under load
• Reduced fuel economy
• Audible pinging or knocking under acceleration in some cases
• Possible hesitation at higher RPM

Here are the most common causes of P0328, ranked by how likely they are to be the culprit:

Generally yes, for short-term driving. With the knock sensor signal stuck high, the ECU pulls ignition timing as a safety measure. The engine still runs but loses power and fuel economy, and persistent knock can damage pistons over time. Fix within a couple of weeks.

Follow these steps to pinpoint the root cause of P0328:

1. Read freeze-frame data and note RPM and load when the code was set. A code set only at high load can point to a wiring fault that opens under engine flex
2. Locate the knock sensor (often under the intake manifold on V6/V8, or on the side of the block on inline engines). Inspect the connector for water, oil, and bent pins
3. Measure resistance across the sensor terminals with the connector unplugged. A typical reading is in the high-kilo-ohm to low-mega-ohm range; an open circuit or near-zero reading both indicate a failed sensor
4. Verify continuity of the signal wire from the sensor connector to the ECU pin. An open in the wire can present as a high-input fault on some ECUs
5. If wiring and sensor are good, scope the signal during a controlled rev to confirm the sensor is producing a clean piezo voltage as the engine vibrates

Repair costs for P0328 vary depending on the root cause and your vehicle. Here are typical estimates:

P0328 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P0328 or indicate related issues: