SFI SYSTEM, Diagnostic DTC:P0171, P0172, P0174, P0175, P1170, P117B

DTC Code DTC Name
P0171 System Too Lean (Bank 1)
P0172 System Too Rich (Bank 1)
P0174 System Too Lean (Bank 2)
P0175 System Too Rich (Bank 2)
P1170 Port Injector Fuel Performance
P117B Direct Injector Fuel Performance

DESCRIPTION

The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim consists of both the short-term and the long-term fuel trim.

The short-term fuel trim is fuel compensation that is used to constantly maintain the air fuel ratio at stoichiometric levels. The signal from the air fuel ratio sensor indicates whether the air fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air fuel ratio is rich and an increase in the fuel injection volume if it is lean.

Factors such as individual engine differences, wear over time and changes in operating environment cause short-term fuel trim to vary from the ideal theoretical value. The long-term fuel trim controls overall fuel compensation. The long-term fuel trim compensates for long term deviations of the fuel trim from the ideal theoretical value. These long term deviations result from the corrections made by the short-term fuel trim.

If both the short-term fuel and long-term fuel trims are lean or rich beyond predetermined values, it is interpreted as a malfunction, and the ECM illuminates the MIL and sets a DTC.

DTC No. DTC Detection Condition Trouble Area

P0171

P0174

Fuel trim is too lean

(2 trip detection logic)


  • Intake system

  • Injector assembly for port injection

  • Injector assembly for direct injection

  • Mass air flow meter sub-assembly

  • Engine coolant temperature sensor

  • Fuel pressure

  • Gas leaks from exhaust system

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • Air fuel ratio sensor heater (bank 1, 2 sensor 1)

  • Air fuel ratio sensor heater (bank 1, 2 sensor 1) circuits

  • PCV valve and hose

  • PCV hose connections

  • ECM

P0172

P0175

Fuel trim is too rich

(2 trip detection logic)


  • Mass air flow meter sub-assembly

  • Engine coolant temperature sensor

  • Injector assembly for port injection

  • Injector assembly for direct injection

  • Ignition system

  • Fuel pressure

  • Gas leaks from exhaust system

  • Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit

  • Air fuel ratio sensor (bank 1, 2 sensor 1)

  • Air fuel ratio sensor heater (bank 1, 2 sensor 1)

  • Air fuel ratio sensor heater (bank 1, 2 sensor 1) circuits

  • ECM

P1170 With stable air fuel ratio feedback, a fuel injection system malfunction has been detected and fuel trim of the port injection is unusually rich or lean side.
  • Injector assembly for port injection

  • Injector assembly for direct injection

  • Fuel pressure

  • ECM

P117B With stable air fuel ratio feedback, a fuel injection system malfunction has been detected and fuel trim of the direct injection is unusually rich or lean side.

Tech Tips

If the vehicle runs out of fuel, the air fuel ratio is lean and DTC P0171 or P0174 may be set. The MIL is then illuminated.

MONITOR DESCRIPTION

Under closed-loop fuel control, fuel injection volumes that deviate from those estimated by the ECM cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the ECM's estimated fuel injection volumes also affect the average fuel trim learning value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learning value of the air fuel ratio). If the average fuel trim learning value exceeds the malfunction threshold, the ECM interprets this as a fault in the fuel system and sets a DTC.


A0162SSE36

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation using the intelligent tester.


  1. Connect the intelligent tester to the DLC3.

  2. Start the engine and turn the tester ON.

  3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

  4. On the intelligent tester, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor.

  5. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

  6. Monitor the output voltages of the air fuel ratio sensors and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

Tech Tips


  • The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.

  • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Tester Display (Sensor) Injection Volume Status Voltage

AFS B1 S1 or AFS B2 S1

(Air fuel ratio)

+25% Rich Less than 3.0 V

AFS B1 S1 or AFS B2 S1

(Air fuel ratio)

-12.5% Lean More than 3.35 V

O2S B1 S2 or O2S B2 S2

(Heated oxygen)

+25% Rich More than 0.55 V

O2S B1 S2 or O2S B2 S2

(Heated oxygen)

-12.5% Lean Less than 0.4 V

Note

The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

Case Air Fuel Ratio Sensor (Sensor 1) Output Voltage Heated Oxygen Sensor (Sensor 2) Output Voltage Main Suspected Trouble Area
1 A0162ADE01 A0160FEE01 A0162ADE01 A0161P9E01 -
2 A0162ADE01 A015ZP2E01 A0162ADE01 A0161P9E01
  • Air fuel ratio sensor

  • Air fuel ratio sensor heater

  • Air fuel ratio sensor circuit

3 A0162ADE01 A0160FEE01 A0162ADE01 A015ZP2E01
  • Heated oxygen sensor

  • Heated oxygen sensor heater

  • Heated oxygen sensor circuit

4 A0162ADE01 A015ZP2E01 A0162ADE01 A015ZP2E01
  • Injector assembly

  • Fuel pressure

  • Gas leaks from exhaust system (Air-fuel ratio extremely rich or lean)


Tech Tips


  • Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

  • A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.

  • A high air fuel ratio sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174, P0175, P1170 OR P117B)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Enter the following menus: Powertrain / Engine / DTC.

    4. Read the DTCs.

      Result
      Result Proceed to
      DTC P0171, P0172, P0174, P0175, P1170 and/or P117B are output A
      DTC P0171, P0172, P0174, P0175, P1170 and/or P117B and other DTCs output B

      Tech Tips

      If any DTCs other than P0171, P0172, P0174, P0175, P1170 or P117B are output, troubleshoot those DTCs first.


    B
    A
  2. READ VALUE USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and turn the tester ON.

    3. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Port.

    4. Read the value.


      1. Select: Data List / A/F Control System / Short FT #1 and Long FT #1 and/or Short FT #2 and Long FT #2.

      OK
      Short FT #1, #2 + Long Ft #1, #2 = Between -19% and +19%
    5. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Direct.

    6. Read the value.


      1. Select: Data List / A/F Control System / Short FT #1 and Long FT #1 and/or Short FT #2 and Long FT #2.

        OK
        Short FT #1, #2 + Long Ft #1, #2 = Between -19% and +19%
        Result
        Item Proceed to
        Port Direct
        OK OK A
        OK NG B
        NG OK C
        NG NG D

    B
    C
    D
    A
  3. CHECK IF VEHICLE HAS RUN OUT OF FUEL IN PAST


    1. Has the run out of fuel in the past?


    NO
    YES
  4. CHECK PCV HOSE

    OK
    PCV hose is connected correctly and is not damaged.

    NG
    OK
  5. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leakage Click here.

      OK
      No leaks from intake system.

    NG
    OK
  6. PERFORM ACTIVE TEST USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and turn the tester ON.

    3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

    4. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor.

    5. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

    6. Monitor the output voltages of the air fuel ratio sensors and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

      Tech Tips


      • The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.

      • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

      Tester Display (Sensor) Injection Volume Status Voltage

      AFS B1 S1 or AFS B2 S1

      (Air fuel ratio)

      +25% Rich Less than 3.0 V

      AFS B1 S1 or AFS B2 S1

      (Air fuel ratio)

      -12.5% Lean More than 3.35 V

      O2S B1 S2 or O2S B2 S2

      (Heated oxygen)

      +25% Rich More than 0.55 V

      O2S B1 S2 or O2S B2 S2

      (Heated oxygen)

      -12.5% Lean Less than 0.4 V
      Result

      Status

      AFS B1 S1

      or

      AFS B2 S1

      Status

      O2S B1 S2

      or

      O2S B2 S2

      Air fuel ratio Condition and

      Air fuel ratio Sensor Condition

      Misfire Suspected Trouble Area Proceed to
      Lean/Rich Lean/Rich Normal - - A
      Lean Lean Actual air fuel ratio lean May occur
      • PCV valve and hose

      • PCV hose connections

      • Injector assembly for port injection

      • Injector assembly for direct injection

      • Gas leaks from exhaust system

      • Intake system

      • Fuel pressure

      • Mass air flow meter sub-assembly

      • Engine coolant temperature sensor

      A
      Rich Rich Actual air fuel ratio rich -
      • Injector assembly for port injection

      • Injector assembly for direct injection

      • Gas leaks from exhaust system

      • Ignition system

      • Fuel pressure

      • Mass air flow meter sub-assembly

      • Engine coolant temperature sensor

      A
      Lean Lean/Rich Air fuel ratio sensor malfunction -
      • Air fuel ratio sensor

      B
      Rich Lean/Rich Air fuel ratio sensor malfunction -
      • Air fuel ratio sensor

      B

      • Lean:


        • During Control the Injection Volume for A/F sensor, the air fuel ratio sensor output voltage (AFS) is consistently more than 3.35 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V.


      • Rich:


        • During Control the Injection Volume for A/F sensor, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V.


    B
    A
  7. READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Enter the following menus: Powertrain / Engine / Data List / All Data / Coolant Temp.

    4. Read the Data List twice, when the engine is both cold and warmed up.

      Standard
      With cold engine
      Same as ambient air temperature.
      With warm engine
      Between 75 and 95°C (167 and 203°F)

    NG
    OK
  8. INSPECT MASS AIR FLOW METER SUB-ASSEMBLY


    1. Inspect the mass air flow meter sub-assembly Click here.


    NG
    OK
  9. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks.

    NG
    OK
  10. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. A015ZERE16

      Disconnect the air fuel ratio sensor connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Bank 1 Sensor 1)
      Tester Connection Condition Specified Condition
      1 (HA1A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω
      1 (HA1A) - 4 (A1A-) Always 10 kΩ or higher
      Standard Resistance (Bank 2 Sensor 1)
      Tester Connection Condition Specified Condition
      1 (HA2A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω
      1 (HA2A) - 4 (A2A-) Always 10 kΩ or higher
    3. Reconnect the air fuel ratio sensor connector.


    NG
    OK
  11. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)


    1. A0160F6E03

      Disconnect the air fuel ratio sensor connectors.

    2. Disconnect the ECM connectors.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      E42-1 (HA1A) - E6-5 (HA1A) Always Below 1 Ω
      E42-3 (A1A+) - E5-23 (A1A+) Always Below 1 Ω
      E42-4 (A1A-) - E5-22 (A1A-) Always Below 1 Ω
      E38-1 (HA2A) - E6-6 (HA2A) Always Below 1 Ω
      E38-3 (A2A+) - E5-21 (A2A+) Always Below 1 Ω
      E38-4 (A2A-) - E5-20 (A2A-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      E42-1 (HA1A) or E6-5 (HA1A) - Body ground Always 10 kΩ or higher
      E42-3 (A1A+) or E5-23 (A1A+) - Body ground Always 10 kΩ or higher
      E42-4 (A1A-) or E5-22 (A1A-) - Body ground Always 10 kΩ or higher
      E38-1 (HA2A) or E6-6 (HA2A) -Body ground Always 10 kΩ or higher
      E38-3 (A2A+) or E5-21 (A2A+) - Body ground Always 10 kΩ or higher
      E38-4 (A2A-) or E5-20 (A2A-) - Body ground Always 10 kΩ or higher
    4. Reconnect the ECM connector.

    5. Reconnect the air fuel ratio sensor connectors.


    NG
    OK
  12. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor Click here.


    NEXT
  13. PERFORM CONFIRMATION DRIVING PATTERN


    1. Connect the intelligent tester to the DLC3.

      A01613WE09
    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Clear the DTCs Click here.

    4. Switch the ECM from normal mode to check mode using the tester Click here.

    5. Start the engine and warm it up with all the accessories switched off. (Procedure "A")

    6. Drive the vehicle at between 60 and 120 km/h (38 and 75 mph) and at an engine speed of between 1400 rpm and 3200 rpm for 3 to 5 minutes. (Procedure "B")

      Tech Tips

      If the system is still malfunctioning, the MIL will be illuminated during procedure "B".

      Note

      If the conditions in this test are not strictly followed, no malfunction will be detected.


    NEXT
  14. CHECK WHETHER DTC OUTPUT RECURS (DTC P0171, P0172, P0174, P0175, P1170 OR P117B)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Enter the following menus: Powertrain / Engine / DTC.

    4. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTCs P0171, P0172, P0174, P0175, P1170 and/or P117B are output B

    A
    B
  15. CHECK FUEL PRESSURE (LOW PRESSURE)


    1. Check the fuel pressure Click here.


    NG
    OK
  16. CHECK FUEL PUMP OPERATION


    1. Check the fuel pump operation Click here.


    NG
    OK
  17. CHECK FUEL LEAK (LOW PRESSURE SIDE)


    1. Check for fuel leaks Click here.

      OK
      No leaks.

    NG
    OK
  18. CHECK FUEL LINE


    1. Check the fuel line for leaks or blockage.

      OK
      No leaks or blockage.

    NG
    OK
  19. CHECK FUEL PRESSURE SENSOR


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Start the engine.

    4. Enter the following menus: Powertrain / Engine / Data List / All Data / Fuel Press.

    5. While revving the engine, check that the fuel pressure fluctuates.

      Standard
      Idling
      3.5 to 4.5 MPa (35.7 to 45.9 kgf/cm2, 508 to 653 psi)
      2000 rpm (No load)
      7 to 9 MPa (61.2 to 102.0 kgf/cm2, 1015 to 1305 psi)

      Tech Tips

      The A/C switch and all accessory switches should be off, and the shift lever should be in N or P, and the engine should be fully warmed up.


    NG
    OK
  20. READ VALUE USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and turn the tester ON.

    3. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection way / Direct.

      Tech Tips

      The A/C switch and all accessory switches should be off, and the shift lever should be in N or P, and the engine should be fully warmed up.

    4. Read the value.


      1. Select: Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).

        Result
        Item Proceed to
        Fuel Pump Duty (D4) Short FT #1 + Long FT #1 Short FT #2 + Long FT #2
        40% or more -20% or less -20% or less A
        10% or less +20% or more +20% or more A
        40% or more +20% or more +20% or more B
        10% or less -20% or less -20% or less C
        10% to 40% - - D

    A
    B
    C
    D
  21. READ VALUE USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and turn the tester ON.

    3. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection way / Direct.

      Tech Tips

      The A/C switch and all accessory switches should be OFF, and the shift lever should be in N or P, and the engine should be fully warmed up.

    4. Read the value of Data List:


      1. Select: Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).

        Result
        Item Proceed to
        Fuel Pump Duty (D4) Short FT #1 + Long FT #1 Short FT #2 + Long FT #2
        10% to 40% -25% or less -25% or less A
        10% to 40% -25% or less -25% to +25% B
        10% to 40% -25% to +25% -25% or less C
        10% to 40% +30% or more +30% or more A
        10% to 40% +25% or more -25% to +25% B
        10% to 40% -25% to +25% +25% or more C
        10% to 40% -25% to +25% -25% to +25% D

    B
    C
    D
    A
  22. CHECK MISFIRE COUNT


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Start the engine.

    4. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Direct.

    5. Allow the engine to idle.

    6. Monitor all of the misfire count values that are displayed on the tester: Powertrain / Engine / Data List / Misfire / Cylinder #1 Misfire Count to Cylinder #8 Misfire Count.

      If no misfire counts occur for any of the cylinders, perform the following procedure:


      1. Move the shift lever to D.

      2. Monitor all of the misfire count values that are displayed on the tester.

        Result
        Misfire Count Proceed to
        No misfire counts, or misfire counts occur randomly in all cylinders A
        Misfire counts occur in particular cylinder B

    B
    A
  23. INSPECT INJECTOR DRIVER (NO. 1 AND NO. 2)


    1. Turn the engine switch off.

    2. Replace the No. 1 and No. 2 injector drivers with normal ones from another vehicle.

      Note

      Do not disconnect and reconnect the connectors with the engine switch on (IG), as the injector driver (EDU) may be damaged.

    3. Connect the intelligent tester to the DLC3.

    4. Start the engine.

    5. Clear the DTCs Click here.

    6. Perform the driving test.

    7. Enter the following menus: Powertrain / Engine / DTC.

    8. Read the DTCs.

      Result
      Result Proceed to
      DTC P0171, P0172, P0174, P0175, P1170 and/or P117B are output A
      DTC is not output B

    B
    A
  24. INSPECT FUEL RELIEF VALVE ASSEMBLY


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester ON.

    3. Start the engine.

    4. Enter the following menus: Powertrain / Engine / Data List / All Data / Fuel Press.

    5. Write down the Fuel Press value.

    6. Turn the engine switch off.

    7. Wait for 10 seconds.

    8. Turn the engine switch on (IG) and turn the tester ON.

    9. Enter the following menus: Powertrain / Engine / Data List / All Data / Fuel Press.

    10. Compare the Fuel Press value from and the fuel pressure value after the engine switch was turned on (IG).

      Result
      Inspection Result Proceed to
      Fuel Press value drops A
      Fuel Press value is maintained B

    A
    B
  25. CHECK FUEL INJECTOR FOR PORT INJECTION


    1. Check the injection volume (whether fuel volume is high or low, and whether injection pattern is poor) Click here.


    NG
    OK