[ Model - ECLIPSE CROSS / Year - 2018 ]
2018 / ECLIPSE CROSS / EC - Workshop Manual
13 -FUEL > 13A-DIRECT INJECTION AND MULTIPOINT FUEL INJECTION (DI AND MPI) > TROUBLESHOOTING > DIAGNOSIS CODE PROCEDURES > CODE NO. P0171 ABNORMAL FUEL SYSTEM (LEAN)
Code No. P0171: Abnormal Fuel System (lean)
 
 
 
 
FUNCTION
  • If the fuel system goes out of order, the fuel correction value will become larger.
  • The engine-ECU checks whether the fuel trim value is within a specified range.
 
 
TROUBLE JUDGEMENT
Check Conditions
  • Either engine coolant temperature is less than 100°C when the engine is started. Or, intake air temperature is less than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is more than 76°C.
  • Fuel injection mode is MPI-mode.
Judgement Criteria
  • Long-term fuel trim is more than +12.5% for 5 seconds.
  • Short-term fuel trim is more than +3.5% for 5 seconds.
or
  • Long-term fuel trim is more than +12.5% for 2 seconds.
  • Short-term fuel trim is more than +25.0% for 2 seconds.
Check Conditions
  • Either engine coolant temperature is less than 100°C when the engine is started. Or, intake air temperature is less than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is more than 76°C.
  • Fuel injection mode is not MPI-mode.
Judgement Criteria
  • Long-term fuel trim is more than +12.5% for 5 seconds.
  • Short-term fuel trim is more than +5.9% for 5 seconds.
or
  • Long-term fuel trim is more than +12.5% for 2 seconds.
  • Short-term fuel trim is more than +25.0% for 2 seconds.
Check Conditions
  • Engine coolant temperature is more than 100°C when the engine is started.
  • Intake air temperature is more than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is more than 76°C.
  • Fuel injection mode is MPI-mode.
Judgement Criteria
  • Long-term fuel trim is more than +12.5% for 5 seconds.
  • Short-term fuel trim is more than +13.7% for 5 seconds.
or
  • Long-term fuel trim is more than +12.5% for 2 seconds.
  • Short-term fuel trim is more than +25.0% for 2 seconds.
Check Conditions
  • Engine coolant temperature is more than 100°C when the engine is started.
  • Intake air temperature is more than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is more than 76°C.
  • Fuel injection mode is not MPI-mode.
Judgement Criteria
  • Long-term fuel trim is more than +12.5% for 5 seconds.
  • Short-term fuel trim is more than +16.0% for 5 seconds.
or
  • Long-term fuel trim is more than +12.5% for 2 seconds.
  • Short-term fuel trim is more than +25.0% for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
PROBABLE CAUSES
  • Failed No. 1 intake air temperature sensor
  • Failed engine coolant temperature sensor
  • Failed manifold absolute pressure sensor
  • Failed air flow sensor
  • Failed barometric pressure sensor in the engine-ECU
  • Failed boost pressure sensor
  • Failed No. 2 intake air temperature sensor
  • Exhaust leak
  • Air intake from air flow sensor and all components downstream of it
  • Failed linear A/F sensor
  • Failed evaporative emission control system
  • Failed positive crankcase ventilation valve
  • Failed injector
  • Failed injector (high pressure)
  • Harness damage in fuel system related part(s) circuit or loose connector contact
  • Incorrect fuel pressure
  • Use of incorrect or contaminated fuel
  • Failed engine-ECU
 
 
DIAGNOSIS PROCEDURE
Preparation to carry out troubleshooting
  • Store the freeze frame data of the diagnosis code P0171.
STEP 1. M.U.T.-IIISE diagnosis code
Is any other diagnosis code than P0171 set?
Inspection chart for diagnosis code (Refer to ).
Go to Step 2.
 
STEP 2. M.U.T.-IIISE data list
  • Data list reference table (Refer to ).
    1. Item 5: No. 1 intake air temperature sensor
    2. Item 6: Engine coolant temperature sensor
    3. Item 8: Manifold absolute pressure sensor
    4. Item 10: Air flow sensor
    5. Item BB: Barometric pressure sensor
    6. Item DE: No. 2 intake air temperature sensor
    7. Item 125: Boost pressure sensor 1
Are the check results normal?
YES : Go to Step 3.
Perform the diagnosis code classified check procedure for the sensor that has shown an abnormal data value. Inspection chart for diagnosis code (Refer to ).
 
STEP 3. Check crankcase emission control system.
  • Positive crankcase ventilation system check (Refer to GROUP 17 - Emission Control - Crankcase Emission Control System - Positive Crankcase Ventilation System Check ).
  • Positive crankcase ventilation valve check (Refer to GROUP 17 - Emission Control - Crankcase Emission Control System - Positive Crankcase Ventilation Valve Check ).
Is the check result normal?
Go to Step 4.
Repair.
 
STEP 4. Check air intake from air flow sensor mounting position and all components downstream of it.
Is the check result normal?
Go to Step 5.
Repair.
 
STEP 5. Check for exhaust leaks
Is the check result normal?
Go to Step 6.
Repair.
 
STEP 6. Check installation status of linear A/F sensor.
Is the check result normal?
Go to Step 7.
Repair.
 
STEP 7. M.U.T.-IIISE data list
  • Data list reference table (Refer to ).
    1. Item E1: Linear A/F sensor
Is the check result normal?
Go to Step 8.
Check linear A/F sensor system. Check code No. P0131: linear A/F sensor circuit low voltage (Refer to ). Check code No. P0132: linear A/F sensor circuit high voltage (Refer to ).
 
STEP 8. Check purge control solenoid valve itself.
  • Purge control solenoid valve check (Refer to GROUP 17 - Emission Control - Evaporative Emission Control System - Purge Control Solenoid Valve Check ).
Is the check result normal?
Go to Step 9.
Replace the purge control solenoid valve.
 
STEP 9. Check of damage in PURG line between purge control solenoid valve connector and engine-ECU connector.
Is the check result normal?
Go to Step 10.
Repair the connector(s) or wiring harness.
 
STEP 10. Check of damage in power supply line between engine control relay connector and purge control solenoid valve connector.
Is the check result normal?
Go to Step 11.
Repair the connector(s) or wiring harness.
 
STEP 11. Check vacuum hose.
  • Vacuum hose check (Refer to GROUP 17 - Emission Control - Vacuum Hose - Vacuum Hose Check ).
Is the check result normal?
Go to Step 12.
Repair.
 
STEP 12. Check evaporative emission control system.
  • Purge control system check (Refer to GROUP 17 - Emission Control - Evaporative Emission Control System - Purge Control System Check ).
  • Purge port vacuum check (Refer to GROUP 17 - Emission Control - Evaporative Emission Control System - Purge Port Vacuum Check ).
Is the check result normal?
Go to Step 13.
Repair.
 
STEP 13. Check canister.
  • Check for leaks from canister or clogged.
Is the check result normal?
Go to Step 14.
Replace the canister.
 
STEP 14. Check injector itself.
  • Injector check (Refer to ).
Is the check result normal?
Go to Step 15.
Replace the injector.
 
STEP 15. Check of damage in INJ1, INJ2, INJ3, INJ4 line between injector connectors and engine-ECU connector.
Are the check results normal?
Go to Step 16.
Repair the connector(s) or wiring harness.
 
STEP 16. Check of damage in power supply line between engine control relay connector and injector connectors.
Are the check results normal?
Go to Step 17.
Repair the connector(s) or wiring harness.
 
STEP 17. Check injector (high pressure) itself.
  • Injector (high pressure) check (Refer to ).
Is the check result normal?
Go to Step 18.
Replace the injector (high pressure).
 
STEP 18. Check of damage in DI-1, DI-2, DI-3, DI-4 line between injector (high pressure) connectors and engine-ECU connector.
Are the check results normal?
Go to Step 19.
Repair the connector(s) or wiring harness.
 
STEP 19. Check of damage in DI+1, DI+2, DI+3, DI+4 line between injector (high pressure) connectors and engine-ECU connector.
Are the check results normal?
Go to Step 20.
Repair the connector(s) or wiring harness.
 
STEP 20. Fuel pressure measurement.
  • Fuel pressure test (Refer to ).
Is the check result normal?
Go to Step 21.
Repair.
 
STEP 21. Check fuel.
  • Check for entry of foreign matter (water, diesel fuel, etc.) into fuel.
Is the check result normal?
Go to Step 22.
Replace the fuel.
 
STEP 22. After checking stored freeze frame data, check diagnosis codes again.
  • If diagnosis code P0171 is set while the vehicle is idling, let the vehicle idle for more than 20 minutes.
  • If diagnosis code P0171 is set while the vehicle is running, let the vehicle run with the same conditions of the freeze frame data, such as the vehicle speed, the crank angle sensor and the coolant temperature sensor, for more than 10 minutes.
Is the diagnosis code P0171 set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).