P1147moderate severityPowertrain
Engine Coolant Temperature Sensor Malfunction
on 2002 Mercedes-Benz SL 3.0L I6 · 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
- Test sensor resistance vs temperature chart
- Inspect connector for corrosion
- Check coolant level at sensor
- Monitor temperature reading during warm-up
- Test wiring continuity to ECU
Repair notes
Replace the engine coolant temperature sensor after verifying proper coolant level.
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P0014
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P0015
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