P1223 – Knock Sensor Signal Low (BMW)

Description

P1223 BMW indicates the knock sensor signal is lower than expected.

Want to confirm the real cause of this fault code?

A high‑quality OBD2 scanner gives you live data, fuel trims, sensor readings and freeze‑frame information — exactly what you need to verify the root cause of this code with confidence.

View Recommended Scanners

Symptoms

  • Rattling under load
  • Hesitation
  • Engine noise

Causes

  • Sensor failure
  • Loose mounting
  • Wiring issue

Diagnosis

  • Check sensor voltage
  • Inspect mounting
  • Check wiring

Repair

  • Replace sensor
  • Retorque sensor
  • Repair wiring