Reductant Heater And Sender Assembly - Transit

The reductant heater and sender assembly contains the pickup tube for the reductant pump module, an electric heating element, a reductant temperature sensor, and an electrode-type level sensor.

The heating element is directly above the pickup tubes inlet filter. When the reductant temperature sensor detects the diesel exhaust fluid (DEF) temperature dropping to its freezing point of -11°C (12°F), the PCM commands the reductant dosage control module (RDCM) to provide voltage to the heating element. The heating element thaws and maintains a pool of liquid reductant within the reductant heater and sender assembly reservoir during cold ambient temperatures.

The reductant level sensor incorporates four stainless steel electrodes, with three electrodes arranged vertically to provide a high, middle, and low level signal. The fourth electrode runs the length of the level sensor and acts as a ground. The DEF is a good conductor of electricity. When the reductant tank is full, the DEF closes a circuit between all three level electrodes and the ground electrode, indicating the tank is full. As the DEF is consumed, the level drops and uncovers each electrode in sequence. The PCM calculates the DEF level based on these signals.

Courtesy of FORD MOTOR CO.