Lost Communication With Turbocharger/Supercharger B Temperature Sensor

Where it lives

For U0689, the description names the sensor as the part involved.

Check these first

• The turbocharger B temperature sensor dropping off the bus
• A broken or shorted wire in the sensor circuit
• Corrosion or oil in the sensor connector
• A failed thermistor inside the sensor
• Loss of reference voltage or ground at the sensor

What to do next

1. Check reference voltage and ground at the turbocharger B temperature sensor
2. Inspect the sensor connector for corrosion or oil
3. Test the sensor signal wire for opens and shorts
4. Read the turbocharger B temperature live data on a scan tool
5. Replace the sensor if it stays offline after the wiring checks
6. Clear the code and retest

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