P0333

Knock/Combustion Vibration Sensor B Circuit High

Q: Is it safe to drive with P0333?

Yes, short-term. You lose a little performance because the ECM retards timing, but the engine is not at immediate risk. Repair it before sustained hard driving.

Q: Can I just clear P0333?

It comes back once the ECM re-checks the circuit. The high signal has to be traced to the sensor or wiring and fixed.

Ignition timing Generic OBD-II Medium

What it means

P0333 means the second knock sensor (bank 2) is sending a higher-than-expected signal to the ECM. Because the computer relies on this sensor to detect knock and fine-tune ignition timing, it retards timing as a safeguard and you may notice slightly less power. It is an electrical circuit fault — it will not prevent the engine from starting.

Medium

Can I keep driving? Usually driveable — with the knock signal lost the ECM retards timing to stay safe, costing a little power and economy but posing no immediate danger.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

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
Slightly reduced power or acceleration
Possible knocking or pinging under load
Small drop in fuel economy

Common causes

Most likely first

Failed knock sensor B (bank 2) reading highLikely
Signal wire shorted to voltage or open in the circuitCommon
Loose or corroded connector at the sensorCommon
ECM fault (rare — check the sensor and wiring first)Less often

How to diagnose & fix

Work through it in order

Scan and read freeze-frame data to confirm the fault is on the bank 2 (sensor B) knock circuit.
Inspect the sensor connector and harness for a short to voltage, chafing, or corrosion.
Measure the knock sensor's resistance and check its mounting torque.
Compare the signal to the other bank's sensor to isolate a bad sensor from wiring.
Replace knock sensor B if it is out of range with good wiring. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0333?+

Yes, short-term. You lose a little performance because the ECM retards timing, but the engine is not at immediate risk. Repair it before sustained hard driving.

Can I just clear P0333?+

It comes back once the ECM re-checks the circuit. The high signal has to be traced to the sensor or wiring and fixed.

Read & clear P0333 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX