P0388moderate severityPowertrain
Auxiliary/Secondary Knock Sensor 2 Circuit High Input
on 2007 Mercedes-Benz S65 AMG 6.0L V12 BiTurbo M275 · RWD
What this code means
The PCM detects an abnormally high voltage signal from the second knock sensor circuit. This can cause the engine to retard timing unnecessarily and reduce performance.
Symptoms
- Reduced engine power
- Check engine light on
- Possible engine pinging
Common causes
- Faulty knock sensor 2
- Short to voltage in wiring
- Corroded sensor connector
- Failed PCM input circuit
Diagnostic steps
- Scan and record freeze frame data
- Inspect knock sensor 2 wiring and connector
- Measure sensor signal voltage with meter
- Replace knock sensor if out of spec
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