Doosan D20S-5 Operation & Maintenance Manual page 122

Operation Section
Table 2. Diagnostic Fault Codes (Flash Codes) cont'd.
DFC PROBABLE FAULT
GasFuelAdaptRangeHi
731 In LPG mode, system had
(73) to adapt lean more than
expected
GasDesEquivHi
In LPG mode, system had
732
to adapt rich more than
expected
GasO2NotActive
Pre-catalyst O2 sensor
741 inactive on LPG, open O2
(74) sensor signal or heater
leads, defective O2
sensor
GasPostO2NotActive
Post-catalyst O2 sensor
inactive on LPG, open O2
742
sensor signal or heater
leads, defective O2
sensor.
743 GasCatInactive
GasO2FailedLean
Pre-catalyst O2 sensor
751
indicates extended lean
operation on LPG
FAULT ACTION *
(1) TurnOnMil
(2) Disable
GasO2 Ctrl
(3) Disable
GasPost O2Ctrl
(Certified Units Only)
None
(1) TurnOnMil
(2) DisableGas
O2Ctrl
(3) Disable
GasPost O2Ctrl
(Certified Units Only)
(1) TurnOnMil
(2) DisableGasPost
O2Ctrl
(Certified Units Only)
None
(1) TurnOnMil
(2) DisableGas
O2Ctrl
(3) Disable
GasPost O2Ctrl
(Certified Units Only)
-120-
CORRECTIVE ACTION FIRST CHECK
Check dual dither valves, e.g. plugged valve or
hose.
Check for plugged orifice(s).
N/A
Check that Pre-catalyst O2 sensor connections
are OK.
O2 (signal) Pin 3 to SECM Pin B13
O2 Pin 2 (HEATER GND) to SECM (DRVG
GNG) Pins A16, B17
O2 Pin 1 (HEATER PWR) to SECM (DRVP +
12V) Pin A23
Verify O2 sensor heater circuit is operating by
measuring heater resistance (2.1Ω ± 0.4Ω)
O2 Pin 2 (HEATER GND) to Pin 1 (HEATER
PWR)
Check that Post-catalyst O2 sensor
connections are OK.
O2 (signal) Pin 3 to SECM Pin B19
O2 Pin 2 (HEATER GND) to SECM (DRVG
GNG) Pins A16, B17
O2 Pin 1 (HEATER PWR) to Post O2 Heater
Relay. Relay pin 87. This relay only turns on
after engine has been running for some time
and SECM has calculated that water
condensation in exhaust has been removed by
exhaust heat. Post O2 Heater Relay has
SECM (DRVP + 12V) applied to the relay coil
power. The relay coil ground is controlled by
SECM Pin A20 to activate the relay to flow
current through the post O2 heater.
Verify O2 sensor heater circuit is operating by
measuring heater resistance (2.1Ω ± 0.4Ω)
O2 Pin 2 (HEATER GND) to Pin 1 (HEATER
PWR)
N/A
Check for vacuum leaks.
Check dual dither valves, e.g. leaking valve or
hose.
Check for missing orifice(s).