OBD-II code · Network
U0629 Lost Communication With A/C Refrigerant Temperature Sensor B
The vehicle bus reports loss of communication with smart A/C refrigerant temperature sensor B. Superheat / subcool calculation switches to a substitute model.
Is it safe to drive with U0629?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
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
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- AC Refrigerant Temp Sensor B, Vehicle Bus Wiring
Related codes
- U0627Lost Communication With A/C Refrigerant Temperature Sensor A
- U0626Lost Communication With A/C Refrigerant Pressure Sensor A
- U0628Lost Communication With A/C Refrigerant Pressure Sensor B
- U062ALost Communication With A/C Refrigerant Distribution Valve Actuator A
- U062BLost Communication With A/C Refrigerant Distribution Valve Actuator B
- U062CLost Communication With A/C Refrigerant Distribution Valve Actuator C
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.