HV Battery Expansion Valve Sticking. The high-voltage battery is cooled by refrigerant as part of the vehicle's AC system. It is regulated using an expansion valve at the base of the battery itself. This expansion valve can become stuck in the open position, either intermittently or permanently. Fault code 21F107 - Cooling valve: valve couldn't be closed will be stored in the SME. CAUSE 1. Excess material from the manufacturing process can become lodged in the valve, causing it to stick open. 2. The diagnostic software in the SME control unit is not robust enough and can lead to a fault being set when a particular threshold is reached, despite the fact that the valve is not actually sticking.
