Hino 238, Workshop Manual

Page: 838 / 919

DEF SCR SYSTEM (DCU) 5–272
CHECKLIST: P20E9
DTC: P20E9 Back flow line check Inspection Procedure
Step Action Description Judgement
Check
(Yes/No)
Yes No
1
Check the
DTC detected
(DCU) [Hino-
DX]
Check if P20E8 has been
detected in [DCU].
DTC P20E8
has been
detected: Go
to YES.
No DTC has
been detected:
Go to NO.
Proceed to
DTC P20E8
diagnosis pro-
cedure.
Go to step 2.
2
Inspect the
leak of the
DEF pipe
[Hino-DX]
Use Hino-DX active test function
to test the DEF leak
1. Select [DEF addition test] in
[DCU] from the [Check func-
tions] menu after the starter
switch is "ON", and run the
[Leak test].
2. Monitor for 60 seconds the
pressure fluctuations (after
pressure stabilization)
occurred after 60 seconds
from the start of the [Leak
test].
<Standard values>
DEF pressure must not exceed
8,500 hPa {123.3 psi}.
DEF pressure temporarily
exceeded 8,500 hPa {123.3 psi}
but dropped below that value
thereafter.
The measure-
ment corre-
sponds to a
standard
value: Go to
YES.
The measure-
ment does not
correspond to
a standard
value: Go to
NO.
Proceed to
DTC P20E8
diagnosis pro-
cedure.
Go to step 3.
3
Inspect the
DEF pressure
1 (Inspection
of the DEF
hose) [Hino-
DX]
1. Set the starter switch to the
"LOCK" position.
2. Disconnect the DEF hose
(back flow side) between the
DEF tank (1) and the DEF
pump (2) and connect the
SST2.
3. Set the starter switch to the
"ON" position.
4. Perform [Leak test] from
[DEF addition test] of Hino-
DX.
<Standard values>
The DEF pressure is stable in the
8,500 to 9,500 hPa (123.3 to
137.8 psi) range for 60 seconds.
The measure-
ments meet
the standard
value: Go to
YES.
The measure-
ments do not
meet the stan-
dard value: Go
to NO.
Replace the
DEF suction
line.
Perform "After-
inspection
work" of
INFORMA-
TION section.
Go to step 4.