U0256low severityNetwork
Lost Communication With HVAC Right
on 2009 Audi A8 4.2L V8 · AWD
What this code means
The network lost communication with the right-side HVAC control module. Climate control on the right side may not respond.
Symptoms
- No right-side climate control
- HVAC unresponsive
- Temperature settings ignored
Common causes
- Faulty right HVAC module
- Wiring or connector fault
- Power or ground loss
- Bus communication fault
Diagnostic steps
- Scan HVAC modules
- Check module power and ground
- Inspect bus wiring
- Replace HVAC module if faulty
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00003
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U0001
High Speed CAN Communication Bus