OBD-II code · Network
U0647 Lost Communication With Motor Electronics Coolant Pump B
The vehicle bus reports loss of communication with smart motor electronics coolant pump B. Cooling for the drive motor inverter cannot be commanded; derating may follow.
Is it safe to drive with U0647?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
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
- 0.5–3 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Motor Electronics Coolant Pump B, Vehicle Bus Wiring
Related codes
- U0646Lost Communication With Motor Electronics Coolant Pump A
- U0648Lost Communication With Motor Electronics Coolant Pump C
- U0644Lost Communication With Wastegate Position Sensor A
- U0645Lost Communication With Active Air Dam Module
- U0649Lost Communication With Coolant Pump D
- U064ALost Communication With Hybrid/EV Battery Pack Current Sensor A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.