Doosan DA40 - 3. Blocked prefilter in the doser; 4. Blocked filter in the bottom of the tank pick-up unit; 5. Leaking tank pick-up unit

SHOP MANUAL
Engine
Ch 1 page 228
3. Blocked prefilter in the doser
Cause
Grease or dirt has blocked the filter.
Solution
Clean or renew the prefilter that sits in the doser intake. Never use
grease to fit hoses in the SCR system. Only soapy water is premit-
ted to facilitate fitting of hoses.
NOTE: If the filter is blocked by vaseline or parrafin wax, it may be
difficult to see the contamination with the naked eye.
4. Blocked filter in the bottom of the tank pick-up unit
Cause
This filter becomes blocked quickly if someone accidentally fills the
reductant tank with diesel or if a lot of dirt has entered the system.
Solution
If there is an odour of diesel from the reductant tank or if white
contaminants are floating on the surface of the reductant: Clean
the system and renew all filters. To diagnose this fault, connect a
hose from the SCR pump intake to an external container with urea.
If the system can then build pressure, the problem is either a leak-
ing tank pick-up unit or a blocked filter in the bottom of the tank
pick-up unit.
5. Leaking tank pick-up unit
Cause
The tank pick-up unit is leaking, which causes the pump to suck in
air above the surface level of the reductant inside the tank.
Solution
Renew the tank pick-up unit. To diagnose this fault, connect a hose
from the SCR pump intake to an external container with urea. If
the system can then build pressure, the problem is either a leaking
tank pick-up unit or a blocked filter in the bottom of the tank pick-
up unit. The tank pick-up unit must be completely sealed down to
the intake located all the way down at the tank pick-up unit filter.