Knock Sensor 2 Circuit Low Input (Bank 2)
The knock sensor on Bank 2 is sending a weak or no signal to the engine computer, like a microphone that's not picking up sound properly. The ECU can't detect engine knock (pre-ignition) on that side of the engine, which could allow harmful detonation.
The knock sensor generates a voltage signal when vibrations from knock events occur in the cylinder. The ECU monitors this signal's amplitude and frequency against programmed thresholds. A low input voltage below the normal operating range triggers this fault code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Knock Sensor Voltage | 0.5–5.0 volts (AC signal component) | Below 0.1 volts or no signal detected |
| Signal Frequency | 4–8 kHz (typical knock detection range) | Outside acceptable range or absent |
Code P0333 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0333 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.