P1328
Knock Sensor 2 Bank 1 High Input.
- BMW
- Powertrain
- Manufacturer code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 1
- Defined byThe manufacturer
- 3
- AreaIgnition system or misfire
- 28
- FaultThe specific fault in that area
What it means
On BMW, P1328 means the engine control unit has seen a signal from knock sensor 2 on bank 1 that is higher than expected. The knock sensor works as a small microphone on the engine block, and the control unit uses it to detect pre-ignition or detonation. A signal outside the plausible range suggests a wiring or sensor fault, or in some cases real engine noise. The exact sensor layout and signal limits depend on the model and engine.
Symptoms
- Engine warning light on
- Reduced power or flat feel under load
- Ignition timing pulled back, giving poorer economy
- Rough running or pinking under load
- Fault logged with no obvious change in how the car drives
Possible causes
- Faulty knock sensor 2 on bank 1 giving an out-of-range signallikely
- Damaged, chafed or heat-hardened wiring to the knock sensor, including a short to voltagelikely
- Corroded or loose connector at the sensor or control unitpossible
- Incorrect sensor mounting torque or poor contact with the blockpossible
- Real mechanical engine noise such as a loose component, worn bearings or piston slap being picked up by the sensorrare
- Fault inside the engine control unitrare
How to diagnose
- Read all stored codes and the freeze frame data to see load, engine speed and temperature when the fault set, and note any other knock sensor codes.
- Check for a software or technical bulletin for the specific model and engine, as knock sensor layout and diagnosis differ between engines.
- Visually inspect the wiring and connector for knock sensor 2 on bank 1 for chafing, oil contamination, heat damage and corrosion.
- Check that the sensor is fitted correctly and secured to the specified torque, with nothing trapped between the sensor and the block.
- With the engine running, listen for any abnormal mechanical noise that could be genuinely upsetting the sensor.
- Using live data, watch the knock sensor signal at idle and gently wiggle the harness to look for jumps or spikes.
- Test the circuit for continuity and for a short to voltage or earth against the wiring diagram for that model, with the connector unplugged.
- If the wiring tests good, compare the sensor with the other knock sensor reading and replace it if it is suspect, then clear the code and retest.
How to fix
- Replace knock sensor 2 on bank 1 if it is faulty, torqued to the specified value.
- Repair or replace damaged wiring or the section of loom that is chafed or shorted.
- Clean or replace corroded or loose connector terminals.
- Refit the sensor properly with clean mating surfaces if it was loose or poorly seated.
- Repair any underlying mechanical fault that is causing real engine noise.
Can I keep driving?
The car can usually be driven for a short time, but the control unit will retard the timing to protect the engine, so power and economy suffer. Get it checked soon, and avoid heavy loads, especially if the engine sounds rough or pinks.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.