Question; Can someone explain how the ECM calculates the DEF level? I know there are 3 level sensors in the DEF tank, all show active, (so should mean they sense the fluid). But tank level PID shows empty? Before I replaced the DEF pump module they would show active, (not the heater and sensor assy. inside the tank), 100% and tank level PID ok. Performed DEF system resets and level reset. RFQT timed out due to tank level. Hoping someone can shed some light on how this system determines tank empty or OK. Thanks!

Glen Beattie
Technician/Shop Foreman
Rescue Inc.
West Townshend, Vermont, USA