U0643Lost Communication With Turbocharger/Supercharger A 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
- This sensor reports a temperature at charger A, whose exact measuring point the J2012 title leaves open; depending on the design it can watch the compressor outlet or the hot side. GM's tables define charger A as the first one in the exhaust path on series layouts and the bank 1 charger on parallel ones. When the sensor is a digital part, for instance with SENT output, the controller sets U0643 as soon as valid frames stop arriving; analog wiring and range faults go to P2B6E to P2B71 instead, and charger B uses U0689. No manufacturer documents U0643 publicly. Without the temperature the engine management loses a protection input for the charger and usually caps boost, so the engine can feel weak under load.
- What you may notice
- MIL on
- Reduced boost and power
- Further boost-related codes stored
- Likely causes
- LikelyWiring near the charger damaged by heat or chafing
- PossibleConnector loose or corroded
- PossibleSensor electronics failed
- RareEngine controller input fault
- 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: €50 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.