U02AD: Lost Communication With Turbocharger/Supercharger Boost Control B
Standardized SAE J2012 code · U02xx — Lost communication with modules
What does U02AD mean?
The vehicle bus reports loss of communication with boost control module B (electric wastegate or VTG actuator). Boost pressure cannot be commanded; the engine reverts to a low-power fallback.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
- High Bus wiring open or shorted
- Medium Module without power or ground
- Medium Module failed
Likelihood is a general estimate across vehicles; your make and model may differ.
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