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

Common causes

• A failed knock sensor
• Damaged, chafed or corroded wiring to the sensor (on many V engines it runs under the intake manifold, where coolant or oil leaks can corrode it)
• A loose, corroded or broken connector
• A fault in the engine computer (rare)

Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.

Symptoms

• Check engine light
• Slightly reduced power or fuel economy
• Sometimes pinging under load, since the computer can't hear knock

Is it safe to drive?

Usually drivable with a steady light, but avoid hard acceleration and towing until it's fixed, and use at least the fuel grade your owner's manual specifies. If you hear heavy knocking or the light flashes, ease off and have it checked before driving further.

How to check it with a scanner

1. Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
2. With the engine off, find knock sensor 1 and inspect the connector and wiring for corrosion, breaks or rodent damage.
3. Look for coolant or oil leaks pooling around the sensor area.
4. If your service information gives a resistance or output spec for the sensor, check it with a multimeter; many knock sensors can't be judged by resistance alone.
5. On engines where the sensor is under the intake manifold, replacement is a bigger job; consider having a shop confirm the diagnosis first.
6. After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.

A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.

Questions

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