P0329 Knock sensor: signal drops out at times (sensor 1, bank 1)

By: Diagno editorial team · Updated: 2026-10-15

P0329 means: Knock sensor: signal drops out at times (sensor 1, bank 1). The knock sensor listens for engine knock. Drive gently and have the car checked soon. The repair usually costs about €60–350 in Estonia. The most common cause: connector loose, damp or corroded.

What it means

The knock sensor listens for engine knock. If its signal is wrong, the computer retards the ignition to be safe and the engine loses power. The signal drops out now and then. The most common cause is a loose connector or a chafed wire.

What you may notice

• Engine light on
• Less power
• Slightly higher fuel consumption

What could be wrong

1. 1Connector loose, damp or corroded
2. 2Wire broken or chafed
3. 3Faulty sensor
4. 4Engine computer fault (rare)

Repair difficulty: Moderate

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Fill up with the right octane fuel. The sensor is often on the block under the intake, so it may be hard to reach. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the sensor

Standard SAE description: Knock Sensor 1 Circuit Intermittent (Bank 1 or Single Sensor)