OBD CodesWhat it means
A knock sensor is a small microphone bolted to the engine. It listens for knock, a harmful rattling kind of combustion, so the computer can back off the ignition timing. Without a good signal the computer plays safe and retards the timing all the time.
Codes in this group
| Code | Meaning |
|---|---|
| P0325 | Knock sensor 1 circuit fault, bank 1 |
| P0326 | Knock sensor 1 reading out of range, bank 1 |
| P0327 | Knock sensor 1 signal low, bank 1 |
| P0328 | Knock sensor 1 signal high, bank 1 |
| P0329 | Knock sensor 1 signal cuts in and out, bank 1 |
| P0330 | Knock sensor 2 circuit fault, bank 2 |
| P0331 | Knock sensor 2 reading out of range, bank 2 |
| P0332 | Knock sensor 2 signal low, bank 2 |
| P0333 | Knock sensor 2 signal high, bank 2 |
| P0334 | Knock sensor 2 signal cuts in and out, bank 2 |
Bank 1 is the side of the engine that has cylinder 1. Sensor 1 is before the catalytic converter and sensor 2 is after it. More terms explained.
What you may notice
- Slightly less power
- Slightly higher fuel use
- Pinging sound under load in some cases
Common causes
Most likely first:
- A failed sensor
- Corroded connector or damaged wiring, often heat or rodent damage
- A sensor that is loose or over-tightened
- Real engine knock from poor fuel or carbon build-up
What to check first
- Use fuel of the octane grade the maker recommends
- The sensor is often hard to reach, so replacement is usually a workshop job
Have a mechanic confirm. A fault code tells you which system reported a problem, not which part has failed. The same code can have several causes, and they differ between car models. Use this page to understand the code, then have a qualified mechanic test the car before any part is replaced.
After the repair
Once the cause is fixed, the code can be cleared with a scan tool, or the warning light goes out by itself after several trips without the fault. Clearing a code without fixing the cause only hides it for a while. More about clearing codes.
Related codes
Crankshaft and camshaft timing do not agree (P0016), Engine misfire (P0300), Crankshaft position sensor (P0335), Camshaft position sensor (P0340), Ignition coil circuits (P0350), Glow plugs (diesel) (P0380). All codes.
Written in November 2026. These are generic OBD-II codes, the same on all makes. Causes and repair steps differ between models.