6.0L V12 BiTurbo M275โ€ขRWDโ€ขAUTOMATICโ€ขgasโ€ขM275โ€ขturbo
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P1386moderate severityPowertrain

Knock Control Malfunction

on 2012 Mercedes-Benz S65 AMG 6.0L V12 BiTurbo M275 ยท RWD

What this code means

The ECU detected a malfunction in the knock control system. The knock sensor input is not being properly processed or the sensor signal quality is unacceptable for reliable knock detection.

Symptoms

  • Check Engine Light
  • Reduced power
  • Engine may knock under load
  • Safety ignition timing retard active

Common causes

  • Faulty knock sensor
  • Incorrect knock sensor torque
  • Wiring issue or shielding damage
  • ECU internal knock processing fault
  • Engine mechanical noise interfering with detection

Diagnostic steps

  1. Test knock sensor signal quality
  2. Verify sensor mounting torque
  3. Inspect shielded wiring for damage
  4. Check for engine mechanical noises
  5. Test ECU knock channel function

Repair notes

Replace the knock sensor with the correct part and torque to specification.

Other Powertrain codes on this vehicle

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