Doosan D20S-5 Operation & Maintenance Manual page 123

GasPostO2FailedLean
Pre-catalyst O2 sensor
752
indicates extended lean
operation on LPG
GasO2FailedRich
771 Pre-catalyst O2 sensor
(77) indicates extended rich
operation on LPG
(*) Fault actions shown are default values specified by the OEM.
(1) TurnOnMil
(2) DisableGasPost
O2Ctrl
(Certified Units Only)
(1) TurnOnMil
(2) DisableGas
O2Ctrl
(3) DisableGasPost
O2Ctrl
(Certified Units Only)
-121-
Correct other faults that may contribute to 752
(e.g. faults pertaining to dither valves, Pre-Cat
O2, Post Cat O2 sensor)
Check for vacuum leaks
Check for leaks in exhaust, catalytic converter,
HEGO sensors; repair leaks.
Check all sensor connections (see fault 742
corrective actions).
Check dual dither valves, e.g. plugged valve or
hose.
Check for plugged orifice(s).
Operation Section