What does code U0618 mean?

Q: What does code U0618 mean?

Lost Communication With Engine Coolant Bypass Valve D. U0618 is a generic communication fault indicating that a control module on the vehicle's network has lost contact with the engine coolant bypass valve D, which is typically a smart actuator with its own electronics. The module that sets this code has stopped receiving expected messages from that valve, so it cannot confirm the valve's position or command it reliably.

DTC codes / U06xx · Network communication / U0618

U0618Lost Communication With Engine Coolant Bypass Valve D

U0618 is a generic communication fault indicating that a control module on the vehicle's network has lost contact with the engine coolant bypass valve D, which is typically a smart actuator with its own electronics. The module that sets this code has stopped receiving expected messages from that valve, so it cannot confirm the valve's position or command it reliably.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.