A Diesel Emissions Fluid (DEF) Thawing arrangement and method is provided for use with a vehicle having an engine, an Engine Control Module (ECM), an exhaust system, and a Selective Catalyst Reduction (SCR) catalytic device. A DEF injection system is connected to the exhaust system and to the ECM. A DEF tank is connected to the DEF injection system, and is provided with a Urea Quality Sensor (UQS). A coolant loop is connected to the engine and has a Coolant Control Valve (CCV) connected to a control module, and a coolant to DEF heat exchanger. A DEF temperature sensor and an ambient temperature sensor are connected to the control module. The control module is configured to trigger a CCV stuck open fault when the DEF tank temperature exceeds the ambient temperature by a threshold amount for a period of time.