Code U0623 indicates that the vehicle's main control module has lost communication with the electronic coolant pump. This typically occurs when the pump fails to send a response signal over the network, such as the CAN or LIN bus.
The internal electronic control board or motor within the electric coolant pump has failed.
Broken, frayed, or shorted communication wires between the pump and the control module.
Moisture or debris at the pump electrical connector causing a poor connection or high resistance.
A loss of power to the pump prevents it from booting up and communicating with the network.
The PCM or ECM is unable to process signals from the pump network, though this is rare.
Not necessarily. While a failed pump is common, the code only indicates a lack of communication, which can be caused by a broken wire or a blown fuse.
Yes. If the pump does not have electrical power, its internal electronics cannot send data signals to the PCM, resulting in a lost communication code.
No. Communication codes are rarely caused by the PCM. It is far more likely that the issue lies with the pump itself or the wiring harness.