Operation Section Table 2. Diagnostic Fault Codes (Flash Codes) cont’d. (*) Fault actions shown are default values specified by the OEM. 79 DFC PROBABLE FAULT FAULT ACTION * CORRECTIVE ACTION FIRST CHECK 852 LiqPostO2FailedLean Pre-catalyst O2 sensor indicates extended lean operation on gasoline (1) TurnOnMil (2) DisableLiqPost O2Ctrl Correct other faults that may contribute to 852 (e.g. faults pertaining to Injectors, MAP, IAT, Pre-Cat O2, Post Cat O2 sensor) Look for leaks in exhaust, catalytic converter, HEGO sensors; repair leaks. Check all sensor connections (see fault 842 corrective actions).
871 LiqO2FailedRich Pre-catalyst O2 sensor indicates extended rich operation on gasoline (1) TurnOnMil (2) DisableLiquid O2Ctrl High gasoline fuel pressure, perform gasoline pressure test Injector problems, e.g. leaking, defective injector 872 LiqPostO2FailedRich Pre-catalyst O2 sensor indicates extended rich operation on gasoline (1) TurnOnMil (2) DisableLiq PostO2Ctrl Correct other faults that may contribute to 872 (e.g. faults pertaining to Injectors, MAP, IAT, Pre-Cat O2, Post Cat O2 sensor) Look for leaks in exhaust, catalytic converter, HEGO sensors; repair leaks. Check all sensor connections (see fault 842 corrective actions).
911 O2RangeLow Pre-catalyst O2 sensor voltage out of range low, sensor signal shorted to ground (1) TurnOnMil (2) DisableLiquid O2Ctrl (3) DisableGas O2Ctrl Check if O2 sensor installed before the catalyst is shorted to GND or sensor GND. O2 (signal) Pin 3 to SECM Pin B13 SECM (DRVG GND) Pins A16, B17 SECM (XDRG sensor GND) Pin B1 912 O2 PostCatRangeLow _ Post-catalyst O2 sensor voltage out of range low, sensor signal shorted to ground (1) TurnOnMil (2) Disable asoline Post-catalyst O2Ctrl (3) Disable LPG Post-catalyst O2Ctrl Check if O2 installed after the catalyst sensor is shorted to GND or sensor GND. O2 (signal) Pin 3 to SECM Pin B19 Possible sources:
SECM (DRVG GND) Pins A16, B17 and SECM (XDRG sensor GND) Pin B1 921 O2RangeHigh Pre-catalyst O2 sensor voltage out of range high, sensor signal shorted to power (1) TurnOnMil (2) DisableLiquid O2Ctrl (3) DisableGas O2Ctrl 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 922 O2 PostCatRangeHigh _ Post-catalyst O2 sensor voltage out of range low, sensor signal shorted to ground (1) TurnOnMil (2) Disable asoline Post-catalyst O2Ctrl (3) Disable LPG Post-catalyst O2Ctrl Check if O2 sensor installed after catalyst is shorted to +5Vdc or battery.
O2 (signal) Pin 3 to SECM Pin B19 Possible voltage sources: SECM (XDRP + 5V) Pin B24 and SECM (DRVP + 12V) Pin A23 931 FuelTempRangeLow Fuel Temperature Sensor Input is Low normally set if the fuel temperature sensor wire has shorted to chassis ground or the sensor has failed. TurnOnMil Check fuel temp sensor connector and wiring for a short to GND SECM (signal) Pin B14 to FTS Pin 1 SECM (sensor GND) Pin B1 to FTS Pin 2 SECM (system GND) Pin A16, B17 932 FuelTempRangeHigh Fuel Temperature Sensor Input is High normally set if the fuel temperature sensor wire has been disconnected or the circuit has opened to the SECM.
TurnOnMil Check if fuel temp sensor connector is disconnected or for an open FTS circuit SECM (signal) Pin B14 to FTS Pin 1 SECM (sensor GND) Pin B1 to FTS Pin 2