DEF Fluid Pump
(replacement DEF pump kit includes mounting oring and seal, mounting hardware, and priming syringe)
2011 - 2016 Super Duty
F250, F350, F450, F550
Ford uses the term "reductant pump assembly" to describe the DEF pump which is mounted to the top of the DEF heater / sender assembly. The DEF pump is part of the SCR (Selective Catalytic Reduction) system and is responsible for pressurizing the the DEF fluid (a urea solution) to 73 PSI and delivering it to the DEF injector via the reductant pressure line. It contains a diaphragm pressure pump, pressure sensor, purge valve, outlet filter, and internal heating element.
When the PCM commands a reductant injection the
reductant injector opens and the reductant pump operates, filling the
reductant pressure line and the reductant injector to purge the air out
of the system. When all of the air is purged, the reductant injector
closes, allowing the reductant pump
pressure to build. When the vehicle is shut down, the PCM closes the reductant injector and
actuates the reductant pump purge valve, causing the reductant pump to
reverse the pump flow and bleed down the pressure from the reductant
pressure line. The PCM then
opens the reductant injector to allow air to enter the reductant
pressure line, which in turn allows the reductant pump to purge all
remaining reductant from the system and return it to the reductant tank.
The PCM then closes the reductant injector
and returns the reductant pump purge valve to the forward pump position
Due to EPA requirements, faults in the DEF system which cause codes to set may cause the vehicle to operate in derate mode limiting engine power and speed.
replacing any DEF system compoenent for a related code,
please be sure to follow factory diagnostic procedures, paying special
attention to the integrity of wiring and connectors to avoid unnecessary
When replacing the DEF pump it is vital to confirm that the diesel emission fluid has not become contaminated with petroleum (diesel fuel). Contaminated fluid will cause very rapid failure of the new pump assembly. It is also of critical importance to clean the entire top of the DEF tank and area around the top of the pump and sending unit before removing any components. Dirt particles entering the DEF system will also cause immediate failure. Do not use any petroleum products (grease or oil) to lubricate orings and seals in the DEF system. It is recommended to only use DEF for this purpose. Before installing the 6.7 diesel exhaust fluid pump be sure to prime it using the included syringe following the factory procedure.
6.7 DEF fluid pump replaces the following part numbers (and others):
BC3Z5J229L, BC3Z5L227K, BC3Z5L229L, 904-369