Doosan D50S-5 Operation & Maintenance Manual page 115

GasPostO2NotActive GasPostO2NotActive
Post-catalyst O2 sensor Post-catalyst O2 sensor
742 742
inactive on LPG, open O2 inactive on LPG, open O2
sensor signal or heater sensor signal or heater
leads, defective O2 sensor. leads, defective O2 sensor.
743 743
Reserved Reserved
GasO2FailedLean GasO2FailedLean
Pre-catalyst O2 sensor Pre-catalyst O2 sensor
751 751
indicates extended lean indicates extended lean
operation on LPG operation on LPG
GasPostO2FailedLean GasPostO2FailedLean
Pre-catalyst O2 sensor Pre-catalyst O2 sensor
752 752
indicates extended lean indicates extended lean
operation on LPG operation on LPG
GasO2FailedRich GasO2FailedRich
Pre-catalyst O2 sensor Pre-catalyst O2 sensor
771 771
(77) (77)
indicates extended rich indicates extended rich
operation on LPG operation on LPG
(*) Fault actions shown are default values specified by (*) Fault actions shown are default values specified by the OEM.
Table 2. MI-07 Diagnostic Fault Codes (Flash Codes) cont'd. Table 2. MI-07 Diagnostic Fault Codes (Flash Codes) cont'd.
DFC DFC
GasPostO2FailedRich GasPostO2FailedRich
Pre-catalyst O2 sensor Pre-catalyst O2 sensor
772 772
indicates extended rich indicates extended rich
PROBABLE FAULT PROBABLE FAULT
(1) TurnOnMil (1) TurnOnMil
(2) DisableGas (2) DisableGas
Post O2Ctrl Post O2Ctrl
(1) TurnOnMil (1) TurnOnMil
(2) DisableGas O2Ctrl (2) DisableGas O2Ctrl
(1) TurnOnMil (1) TurnOnMil
(2) DisableGas (2) DisableGas
Post O2Ctrl Post O2Ctrl
(1) TurnOnMil (1) TurnOnMil
(2) DisableGas O2Ctrl (2) DisableGas O2Ctrl
the OEM.
114 114
FAULT ACTION FAULT ACTION * *
(1) TurnOnMil (1) TurnOnMil
(2) DisableGas (2) DisableGas
PostO2Ctrl PostO2Ctrl
O2 Pin 1 (HEATER PWR) to Post O2 O2 Pin 1 (HEATER PWR) to Post
Heater Relay. Relay pin 87. This relay Heater Relay. Relay pin 87. This relay
turns on only after engine has been turns on only after engine has been
running for some time and SECM has running for some time and SECM has
calculated that water condensation in calculated that water condensation in
exhaust has been removed by exhaust exhaust has been removed by exhaust
heat. Post O2 Heater Relay has SECM heat. Post O2 Heater Relay has SECM
(DRVP + 12V) applied to the relay coil (DRVP + 12V) applied to the relay coil
power. The relay coil ground is power. The relay coil ground is
controlled by SECM Pin A20 to activate controlled by SECM Pin A20 to activate
the relay to flow current through the the relay to flow current through the
post O2 heater. post O2 heater.
Verify O2 sensor heater circuit is Verify O2 sensor heater circuit is
operating by measuring heater operating by measuring heater
resistance (2.1 resistance (2.1 ± 0.4 ± 0.4 ) )
Ω Ω Ω Ω
O2 Pin 2 (HEATER GND) to Pin 1 O2 Pin 2 (HEATER GND) to Pin 1
(HEATER PWR) (HEATER PWR)
Check for vacuum leaks. Check for vacuum leaks.
Check fuel trim valves, e.g. leaking Check fuel trim valves, e.g. leaking
valve or hose. valve or hose.
Check for missing orifice(s). Check for missing orifi ce(s).
Correct other faults that may contribute Correct other faults that may contribute
to 752 (e.g. faults pertaining to fuel trim to 752 (e.g. faults pertaining to fuel trim
valves, Pre-Cat O2, Post Cat O2 valves, Pre-Cat O2, Post Cat O2
sensor) sensor)
Check for vacuum leaks Check for vacuum leaks
Check for leaks in exhaust, c Check for leaks in exhaust, catalytic
converter, HEGO sensors; repair leaks. converter, HEGO sensors; repair leaks.
Check all sensor connections (see fault Check all sensor connections (see
742 corrective actions). 742 corrective actions).
Check fuel trim valves, e.g. plug Check fuel trim valves, e.g. plugged
valve or hose. valve or hose.
Check for plugged orifice(s). Check for plugged orifice(s).
Operation Section Operation Section
CORRECTIVE ACTION CORRECTIVE ACTION
FIRST CHECK FIRST CHECK
Correct other faults that may contribute Correct other faults that may contribute
to 772 (e.g. faults pertaining to FTVs, to 772 (e.g. faults pertaining to FTVs,
Pre-Cat O2, Post Cat O2 sensor) Pre-Cat O2, Post Cat O2 sensor)
Look for leaks in exhaust, catalytic Look for leaks in exhaust, catalytic
converter, HEGO sensors; repair leaks. converter, HEGO sensors; repair leaks.
O2
atalytic
fault
ged