DTC P0171: Adaptive Fuel System Too Lean
NOTE:
After each repair, clear DTCs. See CLEARING CODES/PCM RESET PROCEDURE
under SELF-DIAGNOSTIC SYSTEM. Turn ignition off and then on. Read DTCs to verify repair is complete. For DLC and PCM connector terminal identification, see CONNECTOR IDENTIFICATION
. For wiring diagrams, see WIRING DIAGRAMS
.
NOTE:
On 1995 models: HO2S 1 is located downstream of pre-catalytic converter for cylinders No. 1, 2 and 3. HO2S 2 is located downstream of pre-catalytic converter for cylinders No. 4, 5 and 6. HO2S 3 is located upstream of pre-catalytic converter for cylinders No. 1, 2 and 3. HO2S 4 is located upstream of pre-catalytic converter for cylinders No. 4, 5 and 6. On XJ6, HO2S 3 and 4 apply to Federal vehicles only.
NOTE:
On 1996-1997 models: There are 2 HO2S "A", one upstream of the pre-catalytic converter and one downstream of the pre-catalytic converter, for cylinders No. 1, 2 and 3. There are 2 HO2S "B", one upstream of the pre-catalytic converter and one downstream of the pre-catalytic converter, for cylinders No. 4, 5 and 6.
NOTE:
This DTC applies to cylinders No. 1, 2 and 3.
- Using scan tool, read DTCs. If DTC P0171 is present, check exhaust system for leaks. Repair exhaust system as necessary. If exhaust system is okay, check for any misfire detected DTCs. Proceed to appropriate DTC test procedure. If no misfire detected DTCs are present, turn ignition off and go to next step.
- Use DVOM and wiring diagram to check continuity of all circuits between each Heated Oxygen Sensor (HO2S) connector terminal No. 2 and PCM. Repair wiring as necessary. If wiring is okay, check continuity of all circuits between each HO2S terminal No. 1 and PCM. Repair wiring as necessary. If wiring is okay, go to next step.
- Check each fuel injector for blockage. Repair or replace injectors as necessary. If injectors are okay, Clear DTCs. Turn ignition off and then on. Read DTCs. If DTC P0171 is not present, repair is complete. If DTC P0171 is present, replace PCM.