Specifications

Operation Section
-122-
Table 2. Diagnostic Fault Codes (Flash Codes) cont’d.
DFC PROBABLE FAULT FAULT ACTION * CORRECTIVE ACTION FIRST CHECK
772
GasPostO2FailedRich
Pre-catalyst O2 sensor
indicates extended rich
operation on LPG
(1) TurnOnMil
(2) DisableGasPost
O2Ctrl
(Certified Units
Only)
Correct other faults that may contribute to 772
(e.g. faults pertaining to FTVs, Pre-Cat O2,
Post Cat O2 sensor)
Look for leaks in exhaust, catalytic converter,
HEGO sensors; repair leaks.
Check all sensor connections (see fault 742
corrective actions
)
.
821
LiqFuelAdaptRangeHi
In Gasoline mode, system
had to adapt lean more
than expected
(1) TurnOnMil
(2) Disable
LiquidO2 Ctrl
(3) Disable LiqPost
O2Ctrl
Check for vacuum leaks.
Low gasoline fuel pressure, perform gasoline
pressure test.
Injector problems, e.g. plugged, defective
in
j
ector.
822 LiqDesEquivHi None N/A
831
LiqFuelAdaptRangeLow
In Gasoline mode, system
had to adapt rich more than
expected
(1) TurnOnMil
(2) Disable
LiquidO2 Ctrl
(3) Disable LiqPost
O2Ctrl
Low gasoline fuel pressure, perform gasoline
pressure test
Injector problems, e.g. leaking, defective
injector.
832 LiqDesEquivLo None N/A
841
LiqO2NotActive
Pre-catalyst O2 sensor
inactive on gasoline, open
O2 sensor signal or heater
leads, defective O2 sensor
(1) TurnOnMil
(2) DisableLiquid
O2Ctrl
(3)DisableLiquid
PostO2Ctrl
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
)
842
LiqPostO2NotActive
Post-catalyst O2 sensor
inactive on gasoline, open
O2 sensor signal or heater
leads, defective O2 sensor.
(1) TurnOnMil
(2) DisableLiqPost
O2Ctrl
(Certified Units
Only)
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
)
843 LiqCatInactive None N/A
851
LiqO2FailedLean
Pre-catalyst O2 sensor
indicates extended lean
operation on gasoline
(1) TurnOnMil
(2) DisableLiquid
O2Ctrl
(3)DisableLiquid
PostO2Ctrl
Check for vacuum leaks.
Low gasoline fuel pressure, perform gasoline
pressure test.
Injector problems, e.g. plugged, defective
in
j
ector
(*) Fault actions shown are default values specified by the OEM.