What it means
Knock sensor A signal is in electrical range but plausibility check fails — typically a loose mounting, wrong torque, or sensor element drift.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Knock sensor 1 monitors combustion vibration on bank 1, or the single sensor on an engine with only one. P0326 sets when the control module sees a signal that is electrically present but does not behave as plausibly expected; loose mounting, incorrect torque, or a drifting sensor element can affect that reading.
Common causes
Most likely first.
- Sensor loose — incorrect torque
- Sensor element drift
- Gateway module routing CAN messages incorrectly
Symptoms
- Check-engine light
- Reduced engine power or acceleration
- Engine knocking may be more noticeable
How to diagnose it
- Review freeze-frame and live data for knock-sensor readings and note the engine load and speed when the signal failed its plausibility check.
- Inspect knock sensor 1 on bank 1, or the single sensor, for secure mounting, damaged wiring, corrosion, and a loose connector.
- Check for engine or accessory vibration that could be reaching the sensor and making its signal implausible.
- Verify the sensor is mounted and tightened according to the manufacturer's specification.
- If the mechanical and wiring checks are sound, test the sensor signal and its path to the control module using the manufacturer's procedure.
Common fixes
- Secure the sensor and tighten it to the manufacturer's specification.
- Repair a loose or corroded connector or damaged sensor wiring.
- Correct a source of abnormal engine or accessory vibration.
- Replace knock sensor 1 on bank 1, or the single sensor, if testing confirms its signal is out of range or drifting.
Can I keep driving?
Limit acceleration and heavy loads until the cause is found; reduced power may occur, and knock may become more noticeable if the module cannot interpret the sensor signal reliably. Persistent audible knocking warrants stopping and checking the engine.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.