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2012 MERCEDES-BENZ S65 AMG
6.0L V12 BiTurbo M275•RWD•AUTOMATIC•gas•M275•turbo
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Repairs423Labor489Torque3427Fluid8DTC1098Battery1Maintenance0Recalls0
P1147moderate severityPowertrain

Engine Coolant Temperature Sensor Malfunction

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

What this code means

The ECU detected a malfunction in the engine coolant temperature sensor circuit. The sensor reading is inconsistent with expected temperature progression or is providing an implausible signal.

Symptoms

  • Check Engine Light
  • Incorrect temperature gauge reading
  • Poor cold-start enrichment
  • Fan may run inappropriately
  • Reduced fuel economy

Common causes

  • Faulty coolant temperature sensor
  • Corroded sensor connector
  • Wiring damage
  • Low coolant level exposing sensor
  • Air pocket near sensor location

Diagnostic steps

  1. Test sensor resistance vs temperature chart
  2. Inspect connector for corrosion
  3. Check coolant level at sensor
  4. Monitor temperature reading during warm-up
  5. Test wiring continuity to ECU

Repair notes

Replace the engine coolant temperature sensor after verifying proper coolant level.

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