P0329
Knock/Combustion Vibration Sensor A Circuit Intermittent
Ignition / knock sensor
Generic OBD-II
Medium
What it means
P0329 means the knock-sensor A circuit is cutting in and out. The knock sensor listens for detonation so the ECM can pull back ignition timing to protect the engine. With an intermittent signal the ECM can't trust it, so it usually defaults to conservative timing — costing a little power and economy rather than causing a breakdown.
Medium
Can I keep driving? Driveable — with an unreliable knock signal the ECM retards timing as a precaution, so you may notice slightly less power or economy, but it won't strand you.
Common symptoms
What you'll notice
- Check-engine light on
- Slightly reduced power or acceleration
- Poorer fuel economy
- Occasional audible knock or ping under load
Common causes
Most likely first
- Intermittent break in the knock-sensor wiring or connectorLikely
- Faulty knock sensorCommon
- Loose or corroded connector or sensor mountingCommon
- Engine noise or vibration mimicking knockLess often
- Faulty ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to see when the dropout occurs.
- Wiggle-test the sensor harness and connector for an intermittent open.
- Check the sensor is torqued correctly to clean bare metal.
- Replace the knock sensor if the signal is erratic.
- If wiring and sensor check out, evaluate the ECM. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0329?+
Yes — the ECM protects the engine with conservative timing. Prolonged real detonation can cause damage, so don't leave it indefinitely.
Can I just clear P0329?+
It'll clear but returns when the intermittent fault recurs; find the loose connection or failing sensor.
Related codes
Often seen with P0329
Read & clear P0329 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX