P0325 — Knock Sensor 1 Circuit (Bank 1 or Single Sensor)

What it means

The engine control module has found the signal of knock sensor 1 on bank 1 to be missing or outside the expected range. The knock sensor is a piezoelectric element bolted to the cylinder block that lets the module hear detonation and retard ignition timing in real time. With the code stored the module falls back to a conservative base timing map, so power drops noticeably and fuel consumption rises.

Likely causes (most common first)

1. Faulty knock sensor: cracked piezo element or moisture ingress
2. Corroded or loose connector, oxidised terminals
3. Chafed or open signal wire between sensor and ECM, broken screen
4. Incorrect sensor bolt torque: loose or overtightened, poor acoustic contact
5. Mechanical engine noise mistaken for knock: worn rod bearings, loose pulley or heat shield
6. Failed knock input circuit inside the ECM

Can you drive with it?

You can drive, but avoid high load and full throttle: detonation is no longer detected and power is reduced.