U0695 indicates that the hybrid/electric vehicle battery pack coolant pump B has lost communication with the control module (e.g., hybrid powertrain control module or battery management system). This typically means the pump module is not sending or receiving data on the controller area network (CAN) bus, often due to a failed pump, wiring fault, or power/ground issue.
The pump's internal electronics (motor controller or communication chip) have failed, preventing it from communicating on the CAN bus. This is the most common root cause for U0695.
Open, short, or high resistance in the CAN bus wires (CAN-H, CAN-L) or power/ground circuits to the pump can disrupt communication. Corrosion at the connector is frequent in high-humidity or salt-belt vehicles.
A blown fuse, broken ground wire, or low battery voltage can prevent the pump module from powering up and communicating. Check the dedicated fuse and relay for the coolant pump circuit.
A problem elsewhere on the hybrid CAN bus (like a shorted termination resistor or another module pulling the bus low) can affect communication with pump B. This is less common but possible if multiple U-codes are present.
Rarely, the module that expects to communicate with pump B has an internal fault. This should only be considered after thoroughly testing the pump, wiring, and bus. Replacing the PCM for U0695 is almost always incorrect.
No. The PCM is rarely the cause of a lost communication code for a specific component. Replacing the PCM for U0695 is almost always a misdiagnosis and a waste of money. The fault is nearly always in the pump module, its wiring, or its power supply.
The pump may still run if it receives a PWM or analog signal, but the communication module inside the pump that reports status on the CAN bus could be dead. The code is about data communication, not just motor operation. A pump can spin yet still have a failed communication circuit.
Yes, if pump B is not actually circulating coolant, the battery pack can overheat, especially under load. Even if the pump appears to run, the control module may not be able to verify flow, leading to reduced performance or a shutdown to protect the battery.
No. Only the pump with the communication fault needs attention. However, if the vehicle has two pumps and one has failed, it's wise to inspect the other for similar age/wear, but replacement is not required unless it also shows a fault.