Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor)
Your knock sensor isn't sending proper signals to the engine computer, like a smoke detector with a dead battery that can't alert you to danger. The engine can't adjust timing properly to prevent harmful detonation.
The ECU monitors the knock sensor's voltage signal to detect engine detonation (abnormal combustion). When detonation occurs, the sensor generates a signal that triggers ignition timing retard. If the signal is absent, too weak, or erratic, the ECU cannot compensate for knock.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Knock Sensor Voltage Signal | 0.2–5.0V AC ripple during acceleration | No signal, constant DC voltage, or irregular pulses |
| Signal Frequency | 5–15 kHz when knock detected | Below 2 kHz or no frequency variation |
Code P0326 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, P0326 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.