Code 712:

GasFuelAdaptRangeLo
In LPG mode, system had to
adapt rich more than expected

Check: Check for vacuum leaks.
Check fuel trim valves, e.g. leaking
valve or hose
Check for missing orifice(s).

Code 772:

GasPostO2FailedRich
Pre-catalyst O2 sensor indicates
extended rich operation on LPG

Check: 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).

Code 921:

O2RangeHigh
Pre-catalyst O2 sensor voltage
out of range high, sensor signal
shorted to power

Check: Check if O2 sensor installed before
catalyst is shorted to +5Vdc or
battery.
O2 (signal) Pin 3 to SECM Pin B13
SECM (XDRP + 5V) Pin B24
SECM (DRVP + 12V) Pin A23