Ford F-650 Owner's Manual page 211

DEF Low Level Warning and Vehicle Consequence
DEF Tank Level
Below initial warning
threshold (10% full)
Below critical
warning threshold
(5% full)
Below initial derate
level (2.5% full)
Empty + engine
intentionally shut
down or in extended
idle
Filling the DEF tank
Your vehicle is equipped with a DEF tank with a blue-capped filler port
The 5 gallon (19.0L) DEF tank is located on the left side of the vehicle
under the cab and the 9 gallon (34.0L) DEF tank is located on the right
side of the vehicle behind the Regular Cab and Super Cabs and under the
Crew Cab. The tank can be filled using a nozzle at a DEF filling station
(similar to fuel fill) or using a DEF bottle with a spout. Motorcraft brand
DEF bottles are recommended. Other aftermarket bottles can be used but
it should have a seal on the spout and an internal vent tube to achieve best
fill performance and prevent overfilling.
Note: Do not put DEF in the fuel tank or any other tank on the vehicle.
This can cause damage to components not covered by your vehicle's
warranty.
2012 F-650/750 (f67)
Supplement, 2nd Printing
USA (fus)
Maintenance and Specifications
Indicator
Consequence
Lamps
None
DEF solid
DEF
None
blinking
DEF
blinking / 40% torque
Amber warning reduction
solid
DEF
40% torque
blinking /
reduction +
Amber warning
5 mph
(8 km/h)
solid /
vehicle speed
Red engine
limit
solid
Remedy
Add minimum of
1 gallon (3.8L)
DEF to 5 gallon
(19.0L) tank or
2 gallons (7.6L)
DEF to 9 gallon
(34.0L) tank
211