U0694 signals that the vehicle's control modules have detected a loss of communication with the coolant pump that manages temperature in the hybrid battery pack. The pump is a key component of the battery's thermal management system.
The pump's internal electronics or motor can malfunction, stopping it from responding to control module commands and causing a lost‑communication DTC.
A loose, dirty, or corroded connector on the pump harness can interrupt power or data signals, triggering the code.
Damaged insulation, chafed wires, or a short in the pump's power or CAN lines can prevent proper signal transmission.
A break or interference on the CAN network that carries pump messages can cause modules to not receive the pump's responses.
A malfunction in the PCM can generate the U0694 code, but this is uncommon and usually accompanied by additional PCM‑related codes.
No. The PCM rarely triggers this code; most often the problem is the pump, its wiring, or a CAN bus connection.
The vehicle may limit power or display warnings, so it is best to address the issue promptly to prevent battery overheating.
No. The fault is isolated to the coolant pump circuit and does not require battery pack replacement.
Prompt repair is recommended because an inoperative coolant pump can cause the battery to overheat and reduce vehicle performance.