Hino 238, Workshop Manual

Page: 832 / 919

DEF SCR SYSTEM (DCU) 5–266
DTC: P20E9
EN01H16F02040F03001052
DTC: P20E9 Back flow line check
INFORMATION
1. Technical description
•
DEF line pressure depends on flow rate of DEF pump.
• DEF pump flow rate is determined by the value supplied from the DEF pressure sensor which is integrated with the
DEF pump.
<Description of malfunction>
• Abnormal pressure in the DEF pipe is detected.
2. DTC set condition
(1) DTC detection condition
Exhaust gas temperature (SCR inlet)
>
150

C {302

F}
Defrosting DEF is done.
(2) Judgement criteria
Immediately after DEF pressure rise
•
DEF line pressure does not decrease or is stable at more than 10,000 hPa for 2 sec. at DEF pump duty cycle 7%.
• When the DEF pressure was not stable for 8 sec. from 8,500 hPa to 9,500 hPa (123.3 psi to 137.8 psi) during a
period of 300 sec.
While Normal monitoring
• DEF line pressure is more than 12,500 hPa (181.3 psi) for 5 sec.
Breather hose
Coolant outlet
Harness connector
Coolant inlet
Coolant inlet
DEF back flow (To DEF tank)
Coolant outlet
DEF pressure line (outlet)
DEF back flow
(To DEF tank)
DEF back flow
(To DEF tank)
DEF tank
DEF pump
DEF circuit
DEF Injector
Inside muffler
To DEF SCR
catalyst
DEF tank
DEF suction line
DEF sensor
(strainer) DEF pump
DEF suction line
DEF suction line
DEF pressure line (outlet)
SAPH16F020400179