OBD-II code · Network
U0649 Lost Communication With Coolant Pump D
The vehicle bus reports loss of communication with smart coolant pump D (electric water pump). Pump speed cannot be commanded; coolant flow falls back to a default duty.
Is it safe to drive with U0649?
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
- Coolant Pump D, Vehicle Bus Wiring
Related codes
- U0623Lost Communication With Coolant Pump A
- U0624Lost Communication With Coolant Pump B
- U062FLost Communication With Coolant Pump C
- U0698Lost Communication With Coolant Pump E
- U0699Lost Communication With Coolant Pump F
- U0646Lost Communication With Motor Electronics Coolant Pump A
- U0647Lost Communication With Motor Electronics Coolant Pump B
- U0648Lost Communication With Motor Electronics Coolant Pump C
- U064ALost Communication With Hybrid/EV Battery Pack Current Sensor A
- U064BLost Communication With Hybrid/EV Battery Pack Current Sensor B
- U064CLost Communication With Hybrid/EV Battery Pack Current Sensor C
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.