Hino 238, Workshop Manual

Page: 166 / 919

ENGINE CONTROL SYSTEM (J08E) 4–943
DTC: P20EE
EN01H16F01030F03001122
P20EE: NOx converting catalyst conversion efficiency
INFORMATION
1. Technical description
•
Deterioration of SCR catalyst is determined by a drop in the purification efficiency.
• Purification efficiency is calculated by upstream and downstream NOx sensors.
•
Besides other factors, purification efficiency may drop due to the increase or decrease of DEF amount supplied to the
sensing unit.
<Description of malfunction>
• Deterioration of DEF SCR catalyst is detected.
2. DTC set condition
(1) DTC detection condition
Conditions below continue for 60 seconds
500 kg/h
≤
Exhaust gas mass flow
<
1,000 kg/h
210

C {410

F}
≤
SCR catalyst temperature
<
260

C {500

F}, and
0 ppm
≤
NOx (SCR upstream)
<
200 ppm
(NOx sensor (SCR upstream) stable and NOx sensor (SCR downstream) stable)
Burner deactivated
(2) Judgement criteria
•
Calculate Average NOx conversion efficiency from NOx sensor (upstream.) and (downstream.) and Exhaust gas
mass flow
Target NOx conversion efficiency (from DCU)
–
Average NOx conversion efficiency
≥
1.0 (at SCR catalyst tempera-
ture = 200

C {392

F})
Supply module
(DEF pump)
Air flow
sensor
DEF
sensor
Exhaust gas
temperature
sensor (SCR inlet)
LFQ
(PSR+)
LFR
LGD
(PSRS)
(PSR+)
(PSRS)
LFP LGF
(PSR-)
(PSR-)
LFJ
(PMP+)
LFL
LG8
(PMPS)
(PMP+)
(PMPS)
LFM LGB
(PMV+)
(PMV+)
LFN LGC
(PMV-)
(PMV-)
LFK LGA
(PMP-)
(PMP-)
LGE
LG9
LE4
LE5
LFG
LFH
(FAT-)
(FAT+)
(EXT-)
(EXT+)
NOx
sensor 1
NOx
sensor 2
%JU
%JZ
%JQ
%KF
%JV
(CA2H)
(CA2L)
(CA2H)
(CA2L)
(CA3H)
%KH
%KG
(CA3L)
(CA3H)
%KE
(CA3L)
%KM
(CA3H)
%KL
(CA3L)
%JR
(CA2H)
%JW
(CA2L)
LE9
LE8
(CANH) (CANL)
H
L
H
L
H
L
H
L
%JS
(CA2H)
%JX
(CA2L)
LED
LEC
(CANH)
(CANL)
KTT K0W KTT (AFT+)
(THA+)
K0W
KTR
KTQ
L2P
LCH
KTS
KTR
KTQ
KTS
(AFGD)
(AFSG)
(AFVB)
(AGD6)
(AFSI)
(AFVB)
L75
L2P
LCH
KTU KTD KTU (AFT-)
(AGD5)
KTD
L75
Engine
ECU
DCU
#S5
#S7
#S5
#S7
#AW
#AV
#AW
#AV
LCM
H
L
(CA1H)
LCN
LF5
LF6
(CA1L) (CAL1)
#CP #CP
#CQ #CQ
#SD #SD
#SF #SF
K6V (CANH)
K6W
(CANL)
H
L
&RE
(CA2H)
&RJ
(CA2L)
&RD
(CA2H)
%KC
(CA2L)
(CAH1)
LEY
LEZ
250K
500K
(CAL0)
(CAH0)
LJM LJN
(CAH1) (CAL1)
LJK
LJL
(CAH0)
(CAL0)
&RF
&RK
(CA2H)
(CA2L)
LEK
LEJ
(CANL)
(CANH)
%KP
%KN
(CA3H)
(CA3L)
BCU
SAPH16F010300734