P0327: Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)

P0327 means the ECU detected a voltage signal from knock sensor 1 (or the single knock sensor on inline-4 engines) that is below the expected range. The knock sensor is a piezo-electric device bolted to the engine block that listens for the high-frequency vibration of detonation. A low input typically points to a failed sensor, damaged wiring, or a poor electrical connection.

P0327 is a electrical-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0327 and illuminates the check engine light.

If your vehicle has triggered P0327, you may notice one or more of these symptoms:

• Check engine light illuminated
• Reduced engine power, especially under acceleration
• Pinging or knocking sound under load
• Reduced fuel economy
• Possible engine hesitation

Here are the most common causes of P0327, ranked by how likely they are to be the culprit:

Generally yes, for short-term driving. You can drive short distances, but the ECU will retard ignition timing as a precaution, reducing power and fuel economy. Sustained driving under load (heavy acceleration, towing, or highway hills) can cause untracked detonation that damages pistons over time. Repair within a few weeks.

Follow these steps to pinpoint the root cause of P0327:

1. Locate knock sensor 1. On inline-4 engines it is bolted to the engine block, typically on the intake side. On V6 and V8 engines, knock sensors often sit in the valley under the intake manifold, which makes access expensive
2. Inspect the connector for corrosion or damage. Disconnect, clean with electrical contact cleaner, and reseat. Clear the code and drive several cycles to see if it returns
3. Measure sensor resistance with a multimeter. Most knock sensors read 4 to 5 megohms at room temperature. A reading near zero or infinity indicates a failed sensor
4. Inspect the wiring from the sensor back to the ECU connector. Look for chafing, rodent damage, or breaks. The wire is a shielded twisted pair on most modern designs
5. If the sensor and wiring are good, verify mounting torque. Knock sensors are torque-sensitive (typically 20 to 25 Nm). Loose or over-tight mounting alters the sensor signal and can trigger P0327

Repair costs for P0327 vary depending on the root cause and your vehicle. Here are typical estimates:

P0327 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 P0327 or indicate related issues: