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Home >> Toyota >> 2006 >> Corolla CE, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Engine Control System (SFI) (2ZZ-GE) - Diagnostics) >> DTC P0171, P0172: System Too Lean/Rich (Bank 1) >> Inspection Procedure >> OBD II scan tool (excluding the hand-held tester):

OBD II scan tool (excluding the hand-held tester):

WARNING: This page is about a different variant/trim than selected.
  1. CHECK AIR INDUCTION SYSTEM 
    1. Check the air induction system for vacuum leakage.

      OK: No leakage from air induction system. 

    1. NG: REPAIR OR REPLACE AIR INDUCTION SYSTEM 
    2. OK: GO TO NEXT STEP 
  2. CHECK PCV HOSE CONNECTIONS 

    OK: PCV hose is connected correctly, and is not damaged. 

    1. NG: REPAIR OR REPLACE PCV HOSE 
    2. OK: GO TO NEXT STEP 
  3. INSPECT FUEL INJECTOR ASSY (INJECTION AND VOLUME) 
    1. Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor).
    1. NG: REPLACE FUEL INJECTOR ASSY 
    2. OK: GO TO NEXT STEP 
  4. READ VALUE USING OBD II SCAN TOOL (COOLANT TEMP) 
    1. Connect an OBD II scan tool to the DLC3.
    2. Turn the ignition switch to ON and turn the scan tool ON.
    3. Read the engine coolant temperature value using the scan tool twice, when the engine is cold and also warmed up.

      Standard: 

      With cold engine: Same as ambient air temperature. 

      With warm engine: Between 75°C and 95°C (167°F and 203°F) 

    1. NG: REPLACE ENGINE COOLANT TEMPERATURE SENSOR 
    2. OK: GO TO NEXT STEP 
  5. READ VALUE USING OBD II SCAN TOOL (MAF) 
    1. Connect the OBD II scan tool to the DLC3.
    2. Turn the ignition switch to ON and turn the scan tool ON.
    3. Allow the engine to idle until the engine coolant temperature reaches 75°C (167°F).
    4. Read the mass air flow rate value with the engine in an idling condition and at an engine speed of 2,500 rpm.

      Standard: 

      Mass air flow rate while engine idling: Between 1.5 gm/s and 5.0 gm/s (A/C: OFF). 

      Mass air flow rate at engine speed of 2,500 rpm: Between 5.0 gm/s and 15.0 gm/s (A/C: OFF). 

    1. NG: REPLACE MASS AIR FLOW METER 
    2. OK: GO TO NEXT STEP 
  6. CHECK FOR SPARKS AND IGNITION 

    OK: Sparks occur. 

    1. NG: REPAIR OR REPLACE 
    2. OK: GO TO NEXT STEP 
  7. CHECK FUEL PRESSURE (See  ON-VEHICLE INSPECTION  ) 
    1. Check the fuel pressure.
    1. NG: REPLACE FUEL SYSTEM 
    2. OK: GO TO NEXT STEP 
  8. CHECK FOR EXHAUST GAS LEAKAGE 

    OK: No gas leakage. 

    1. NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 
    2. OK: GO TO NEXT STEP 
  9. READ VALUE USING OBD II SCAN TOOL (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR) 
    1. Connect the OBD II scan tool to the DLC3.
    2. Turn the ignition switch to ON and turn the scan tool ON.
    3. Start the engine.
    4. Warm up the front Heated Oxygen (HO2) sensor at an engine speed of 2,500 rpm for approximately 90 seconds.
    5. Read the output voltage of the front HO2 sensor using the OBD II scan tool while idling.

      Standard: Fluctuates between less than 0.4 V and more than 0.5 V (refer to table below). 

      Fig 1: Identifying Voltage Fluctuation Of HO2 Sensor
      G02599295Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: Go to step   16 
    2. OK: GO TO NEXT STEP 
  10. PERFORM CONFIRMATION DRIVING PATTERN 
    Fig 2: Performing Confirmation Driving Pattern
    G02599296Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Connect the OBD II scan tool to the DLC3.
    2. Turn the ignition switch to ON and turn the scan tool ON.
    3. Clear DTCs (see DTC CHECK/CLEAR ).
    4. Start the engine.
    5. Warm up the engine.
    6. Drive the vehicle at 31 mph (50 km/h) or more for 3 to 5 minutes.
    7. Allow the engine to idle for 2 minutes.
    8. Repeat steps (f) and (g) above at least 3 times.
    9. Turn the ignition switch to OFF and repeat steps from (d) through (h) described above.

      NEXT: OK GO TO NEXT STEP 

  11. CHECK WHETHER DTC OUTPUT RECURS ( DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 
    1. Read DTCs using the OBD II scan tool.

      Result: 

      DTC OUTPUT RESULT

      Display (DTC Output) Proceed To
      P0171 or P0172 A
      No output B
    1. B: Go to step   15 
    2. A: OK GO TO NEXT STEP 
  12. REPLACE HEATED OXYGEN SENSOR (SENSOR 1) 

    NEXT: OK GO TO NEXT STEP 

  13. PERFORM CONFIRMATION DRIVING PATTERN (REFER TO STEP   10 ) 

    NEXT: OK GO TO NEXT STEP 

  14. CHECK WHETHER DTC OUTPUT RECURS ( DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 
    1. Read DTCs using the OBD II scan tool.

      Result: 

      DTC OUTPUT RESULT

      Display (DTC Output) Proceed To
      No output A
      P0171 or P0172 B
    1. B: REPLACE ECM (See  ECM (1ZZ-FE/2ZZ-GE) REPLACEMENT  ) AND PERFORM CONFIRMATION DRIVING PATTERN (Refer to step   10 ) 
    2. A: OK GO TO NEXT STEP 
  15. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST 
    1. NO:  CHECK FOR INTERMITTENT PROBLEMS  
    2. YES: OK GO TO NEXT STEP 

      DTC CAUSED BY RUNNING OUT OF FUEL ( DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 

  16. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE) 
    1. Disconnect the H5 HO2 sensor connector.
    2. Measure the resistance between the terminals of the HO2 sensor connector.

      Standard: 

      HEATED OXYGEN SENSOR (HEATER RESISTANCE)

      Tester Connections Specified Conditions
      HT (H5-2) - +B (H5-1) Between 5 Ω and 10 Ω 20°C (68°F)
      HT (H5-2) - E (H5-3) 10 kΩ or higher
    3. Reconnect the HO2 sensor connector.
      Fig 3: Identifying Terminals Of H5 Heated Oxygen Sensor Connector
      G02599297Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE HEATED OXYGEN SENSOR 
    2. OK: GO TO NEXT STEP 
  17. INSPECT EFI RELAY 
    1. Remove the EFI relay from the engine room R/B.
    2. Check the EFI relay resistance.

      Standard: 

      EFI RELAY RESISTANCE

      Tester Connections Specified Conditions
      3-5 10 kΩ or higher
      3-5 Below 1Ω (When battery voltage applied to terminals 1 and 2)
    3. Reinstall the EFI relay.
      Fig 4: Inspecting EFI Relay
      G02599298Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE EFI RELAY 
    2. OK: GO TO NEXT STEP 
  18. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM) 
    1. Disconnect the H5 HO2 sensor connector.
    2. Disconnect the E4 ECM connector.
    3. Check the resistance.

      Standard (Check for open): 

      HEATED OXYGEN SENSOR - ECM RESISTANCE (CHECK FOR OPEN)

      Tester Connections Specified Conditions
      HT (H5-2) - HT1A (E4-6) Below 1 Ω
      OX (H5-4) - OX1A (E4-22) Below 1 Ω
      Fig 5: Identifying Terminals Of H5 Heated Oxygen Sensor Connector
      G02599299Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard (Check for short): 

      HEATED OXYGEN SENSOR - ECM RESISTANCE (CHECK FOR SHORT)

      Tester Connections Specified Conditions
      HT (H5-2) or HT1A (E4-6) - Body ground 10 kΩ or higher
      OX (H5-4) or OX1A (E4-22) - Body ground 10 kΩ or higher
    4. Reconnect the ECM connector.
    5. Reconnect the HO2 sensor connector.
      Fig 6: Disconnecting E4 ECM Connector
      G02599300Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 7: System Diagram Of Bank 1 Sensor 1
      G02599301Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: GO TO NEXT STEP 
  19. REPLACE HEATED OXYGEN SENSOR (SENSOR 1) 

    NEXT: OK GO TO NEXT STEP 

  20. PERFORM CONFIRMATION DRIVING PATTERN (REFER TO STEP   10 ) 

    NEXT: OK GO TO NEXT STEP 

  21. CHECK WHETHER DTC OUTPUT RECURS ( DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 
    1. Read DTCs using the OBD II scan tool.

      Result: 

      DTC OUTPUT RESULT

      Display (DTC Output) Proceed To
      No output A
      P0171 or P0172 B
    1. B: REPLACE ECM (See  ECM (1ZZ-FE/2ZZ-GE) REPLACEMENT  ) AND PERFORM CONFIRMATION DRIVING PATTERN (Refer to step   10 ) 
    2. A: OK GO TO NEXT STEP 
  22. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST 
    1. NO:  CHECK FOR INTERMITTENT PROBLEMS  
    2. YES: OK GO TO NEXT STEP 

      DTC CAUSED BY RUNNING OUT OF FUEL ( DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 

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