Code U0649 indicates that the vehicle's main control module has lost communication with the electronic control module of Coolant Pump D. This is a network-related fault where the pump is no longer sending or receiving data on the communication bus.
The internal electronics or the integrated control module within the pump have failed, preventing it from communicating.
Frayed, broken, or shorted communication wires leading to the pump, often caused by abrasion or rodent damage.
Moisture intrusion or corrosion at the pump's electrical connector causing a loss of signal integrity.
A blown fuse or failed relay preventing the pump module from receiving the power necessary to operate its communication hardware.
Network noise or a fault in another module causing a communication timeout for the pump.
A failure in the PCM or ECM network interface, though this is highly unlikely compared to hardware or wiring faults.
Not usually; a mechanical jam typically triggers a current-draw code. U0649 specifically refers to a failure in the electronic communication between the pump's module and the vehicle network.
No. Communication codes are rarely caused by the PCM. It is far more likely that the pump itself has failed or there is a break in the wiring harness.
It depends on the pump's function. If it is critical for battery cooling in a hybrid/EV or engine cooling, continued operation can lead to overheating and permanent component damage.