Diesel Exhaust Fluid Heater Control Unit

WARNING: This page is about a different car, the 2019 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

The DEF heater control unit is located in the left side of the spare wheel well. The heater system enables rapid Selective Catalyst Reduction (SCR) system operation in the event of the frozen DEF. The heater system ensures an adequate quantity of defrosted DEF is available at all operating points. The DEF heater control unit has a switched power supply from the Engine Junction Box (EJB). The Powertrain Control Module (PCM) controls the EJB.

The DEF heater control unit has hardwired connections to the DEF tank module and the DEF line heater element. If the ambient air temperature is below -7°C (19.4°F) the PCM switches on the DEF heater control unit via the Private Controller Area Network (CAN) bus. The DEF heater control unit energizes the heater elements, located in the DEF tank module and in the DEF line. The DEF heater control unit has on-board diagnostics to detect and report faults to the PCM via the Private CAN bus.