P2681: Coolant bypass valve open-load detection is an electrical finding

P2681 is engine coolant bypass valve A control circuit/open. Ford’s diesel summary identifies the monitored event as an open actuator load reported by the power stage. It does not directly measure whether coolant reaches the expected temperature or whether the valve physically moves freely.

The output driver supplies the classification

The check runs continuously with a typical five-second monitoring duration. Ford lists no separate sensor prerequisite for this circuit monitor. P2682 and P2683 on the same page identify short-to-ground and short-to-power classifications, respectively.

Those distinctions matter because a cold-running complaint alone cannot establish an open electrical load. Conversely, an open-load report does not identify the valve’s hydraulic position or prove a stuck thermostat.

Connect the code to the correct controlled valve

Useful verification starts with the vehicle’s actual coolant-bypass actuator circuit and its power-stage diagnostic information. The code’s A designation is not a universal physical location across engine layouts.

Ford does not provide a connector pinout, a resistance threshold, or an isolation sequence in this summary. It also does not distinguish a disconnected harness, actuator fault, or driver problem from the open-load report alone. Use the correct service procedure before selecting a valve or controller replacement. The monitor’s contribution is the electrical classification and its persistence, which should remain separate from temperature-performance diagnosis and any work on a hot, pressurized cooling system.

Source and applicability

This explanation follows Ford’s 2023–2024 diesel OBD summary. Match the vehicle’s engine and calibration before applying these monitor values; a generic code alone does not establish fitment. Ford PDF, page 103.