P2681 Possible Causes
- Faulty engine coolant bypass valve
- Engine coolant bypass valve harness is open or shorted
- Poor electrical connection in engine coolant bypass valve circuit
How to Fix Code P2681
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Engine light on (or service engine soon warning light)
P2681 Meaning
The cabin heater coolant control valve regulates the flow of engine coolant into the cabin heater loop based on engine coolant temperature and ambient temperature conditions. The cabin heater coolant control valve has two positions: Bypass or Link. In Bypass position, the coolant in the engine loop and heater loop is separated and in Link position, the coolant flows through both loops. The valve movement is controlled by a PWM signal. A 50% duty cycle is a normal duty cycle. A 75% duty cycle represents a valve commanded to Link position. A 25% duty cycle represents a valve commanded to Bypass position. The cabin heater coolant control valve uses an internal position sensor that sends a signal to the hybrid powertrain control module to determine the valve position.
When the engine coolant temperature heats up, a valve learning procedure takes place. The hybrid powertrain control module 2 commands the valve to Link position and records the voltage returning from the position sensor. The hybrid powertrain control module 2 then commands the valve to Bypass position and records the voltage returning from the position sensor. The voltage values in Link and Bypass positions must be within calibrated ranges…