U0698 indicates that a control module (usually the powertrain control module) has lost serial‑data communication with the electric coolant pump E. The code is set when the expected messages from the pump controller are missing on the controller‑area network (CAN) for a programmed period, meaning the pump is not being commanded or its status is not being reported.
The pump’s internal motor can burn out, seize, or develop open/short circuits, preventing it from responding to commands and causing loss of communication.
A separate controller that drives the pump may fail internally, losing its ability to transmit data on the CAN bus even though power is present.
Open, shorted, or high‑resistance circuits between the pump and the network (including the 12 V power, ground, and CAN lines) will block communication.
If the fuse supplying voltage to the pump circuit is open or the relay is stuck, the pump will not receive power and cannot communicate.
A problem on the controller‑area network—such as damaged bus wiring, incorrect termination resistance, or another malfunctioning node—can prevent the pump’s messages from reaching the PCM.
Rarely, the control module itself may fail to process the pump’s data correctly; this should be considered only after all other causes have been ruled out.
If the electric coolant pump is not functioning, the engine may overheat; it is unsafe to drive until the fault is diagnosed and repaired.
No. In most cases the problem lies in the pump, its controller, wiring, or a CAN bus fault; PCM replacement is rarely required.
The engine may enter a reduced‑power mode and rely on any remaining mechanical cooling, but the risk of overheating remains high.
A damaged connector can cause an open circuit, preventing the pump from receiving power or communicating, which will set U0698.