Knock/Combustion Vibration Sensor A Circuit High
What it means
P0328 means the knock sensor "A" signal is reading higher than the valid range. The knock sensor lets the ECM detect engine knock (detonation) and pull ignition timing to protect the engine; with the signal faulted, the ECM defaults to more conservative timing, costing a little power and economy. It's usually the sensor or its wiring — often a short to voltage on the signal wire.
Can I keep driving? Yes — the car drives, but with the knock sensor out the ECM pulls timing as a precaution, so expect slightly reduced power and economy.
Real-world scan data
Appears alongside · share of P0328 scans
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power and throttle response
- Slightly reduced fuel economy
- Possible engine knock or pinging under load
Common causes
Most likely first
- Faulty knock sensor — most commonLikely
- Damaged, corroded, or shorted wiring/connector in the sensor circuitCommon
- Signal wire shorted to voltage (drives the reading high)Common
- Poor sensor groundLess often
- Faulty ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and note whether the high-signal fault is constant or intermittent.
- Locate the knock sensor (usually on the engine block) and inspect its connector and wiring for damage or corrosion.
- Check for a short to voltage on the signal wire and verify a clean sensor ground.
- Measure the sensor's resistance/output against spec; replace it if out of range.
- Clear the code and road-test; confirm timing is no longer being pulled.
P0328 by make
Based on commonly reported failure patterns across owner and repair communities, not on our scan data.
Chevrolet
On Chevrolet V8 trucks and cars, the knock sensors sit under the intake manifold, so wiring damage and oil leaks onto the sensor are common causes. Replacing one is a bigger job than usual.
Ford
On Ford vehicles, a damaged wire or connector at the knock sensor is a common cause. It can also come from oil dripping onto the connector.
GMC
On GMC V8 trucks and SUVs, the knock sensors sit under the intake manifold, so wiring damage and oil leaks onto the sensor are common causes. Replacing one is a bigger job than usual.
Toyota
On Toyota V6 models, the knock sensors sit under the intake manifold, so replacing one is a bigger job than usual. A damaged harness is a common cause.
FAQ
Quick answers
Is it safe to drive with P0328?+
Can I just clear P0328?+
Related codes
Read & clear P0328 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.