Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
Your knock sensor is sending a weaker-than-normal electrical signal to the engine computer, like a microphone that's turned down too low. This prevents the engine from detecting pinging (detonation) and adjusting timing properly.
The knock sensor generates a voltage signal (typically 0.5–5V AC) when it detects vibrations from detonation. The ECM monitors this signal amplitude and frequency. When the signal drops below the minimum threshold, the ECM cannot reliably detect knock and triggers P0328.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Knock Sensor Voltage | 0.5–5V AC oscillating signal | Below 0.1V or no signal detected |
| Signal Continuity | Continuous during combustion events | Open circuit or intermittent connection |
Code P0328 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, P0328 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.