U0689Lost Communication With Turbocharger/Supercharger B Temperature Sensor
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Twin-charger engines may monitor a temperature at the second charger, for instance to protect the compressor or turbine of charger B from overheating; CARB's diesel data list includes compressor inlet as well as turbine inlet and outlet temperatures. U0689 means the reading of the temperature sensor for charger B arrives over a digital link and that link has failed. Such a channel can be built into a combined pressure sensor, as Infineon's KP276 shows with its SENT-transmitted NTC input. No manufacturer documents U0689 publicly, and none of the Ford or GM summaries examined contains it. Circuit faults of an analog sensor are P2B8F to P2B92, charger A's link loss is U0643. With the value gone, the controller may protect the charger by limiting boost.
- What you may notice
- Check engine light
- Boost reduced as a precaution
- Otherwise often unchanged driving
- Likely causes
- LikelyWiring near charger B damaged by heat
- PossibleConnector loose or corroded
- PossibleTemperature sensor or its interface electronics failed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.