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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 >> Hand-held tester:

Hand-held tester:

WARNING: This page is about a different variant/trim than selected.
  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO  DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 
    1. Connect a hand-held tester to the DLC3.
    2. Turn the ignition switch to ON and turn the tester ON.
    3. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
    4. Read DTCs.

      Result: 

      DTC OUTPUT RESULT

      Display (DTC Output) Proceed To
      P0171 or P0172 A
      P0171 or P0172 and other DTCs B

      HINT: If any DTCs other than P0171 or P0172 are output, troubleshoot those DTCs first.

    1. B: GO TO  DIAGNOSTIC TROUBLE CODE CHART  
    2. A: 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 (See  EMISSION CONTROL SYSTEM (2ZZ-GE)  ) 
    2. OK: GO TO NEXT STEP 
  3. 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 
  4. PERFORM ACTIVE TEST USING HAND-HELD TESTER (A/F CONTROL) 
    1. Connect the hand-held tester to the DLC3.
    2. Start the engine and turn the tester ON.
    3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
    4. On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
    5. Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
    6. Monitor the voltage output of the Heated Oxygen (HO2) sensors (O2S B1S1 and O2S B1S2) displayed on the tester.

    HINT:

    • The A/F CONTROL 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

      Standard: 

      HO2S SENSOR INJECTION VOLUME AND VOLTAGE

      Tester Display (Sensor) Injection Volumes Status Voltages
      O2SB1S1 (Front HO2 Sensor) +25 % Rich More than 0.5
      O2SB1S1 (Front HO2 Sensor) -12.5% Lean Less than 0.4
      O2SB1S2 (Rear HO2 Sensor) +25 % Rich More than 0.5
      O2SB1S2 (Rear HO2 Sensor) -12.5% Lean Less than 0.4

      Result: 

      Fig 1: A/F Control Active Test Result
      G02599288Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Lean: During A/F CONTROL, both the front and rear HO2 sensor output voltages (O2S) are consistently less than 0.4 V.

      Rich During A/F CONTROL, both the O2S voltages are consistently more than 0.5 V.

    1. B: Go to step   11 
    2. C: Go to step   15 
    3. A: GO TO NEXT STEP 
  5. READ VALUE USING HAND-HELD TESTER (COOLANT TEMP) 
    1. Connect the hand-held tester to the DLC3.
    2. Turn the ignition switch to ON and turn the tester ON.
    3. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / COOLANT TEMP.
    4. Read the COOLANT TEMP twice, when the engine is cold and also when 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 
  6. READ VALUE USING HAND-HELD TESTER (MAF) 
    1. Connect the hand-held tester to the DLC3.
    2. Turn the ignition switch to ON and turn the tester ON.
    3. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / MAF and COOLANT TEMP.
    4. Allow the engine to idle until the COOLANT TEMP reaches 75°C (167°F).
    5. Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.

      Standard: 

      MAF while engine idling: Between 1.5 gm/s and 5.0 gm/s (A/C: OFF). 

      MAF 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 
  7. CHECK FUEL PRESSURE (See  ON-VEHICLE INSPECTION  ) 
    1. Check the fuel pressure.
    1. NG: REPAIR OR 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 SYSTEM 
    2. OK: GO TO NEXT STEP 
  9. CHECK FOR SPARKS AND IGNITION 

    HINT: If the spark plugs or ignition system malfunctions, engine misfire may occur. The misfire count can be read using a hand-held tester. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST /ALL/CYL#1 (to CYL#4).

    1. NG: REPAIR OR REPLACE IGNITION SYSTEM 
    2. OK: GO TO NEXT STEP 
  10. INSPECT FUEL INJECTOR ASSY (INJECTION AND VOLUME) 

    HINT: If the injectors malfunction, engine misfire may occur. The misfire count can be read using a hand-held tester. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / CYL #1 (to CYL #4).

    1. NG: REPLACE FUEL INJECTOR ASSY 
    2. OK: GO TO NEXT STEP 
  11. 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 5Ω and 10Ω at 20°C (68°F)
      HT (H5-2)-E (H5-3) 10 kΩ or higher
    3. Reconnect the HO2 sensor connector.
      Fig 2: Identifying Terminals Of H5 Heated Oxygen Sensor Connector
      G02599289Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE HEATED OXYGEN SENSOR 
    2. OK: GO TO NEXT STEP 
  12. 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 1 Ω (When battery voltage applied to terminals 1 and 2)
    3. Reinstall the EFI relay.
      Fig 3: Inspecting EFI Relay
      G02599290Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE EFI RELAY 
    2. OK: GO TO NEXT STEP 
  13. 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 4: Identifying Terminals Of H5 Heated Oxygen Sensor Connector
      G02599291Courtesy 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 5: Disconnecting E4 ECM Connector
      G02599292Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 6: System Diagram Of Bank 1 Sensor 1
      G02599293Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: GO TO NEXT STEP 
  14. REPLACE HEATED OXYGEN SENSOR (SENSOR 1) 

    NEXT: OK GO TO NEXT STEP 

  15. PERFORM CONFIRMATION DRIVING PATTERN 
    Fig 7: Performing Confirmation Driving Pattern
    G02599294Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Connect the hand-held tester to the DLC3.
    2. Turn the ignition switch to ON and turn the tester ON.
    3. Clear DTCs (see DTC CHECK/CLEAR ).
    4. Switch the ECM from normal mode to check mode using the tester (see CHECK MODE PROCEDURE ).
    5. Start the engine and warm it up with all accessaries switched OFF.
    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.

    HINT: If the system is still malfunctioning, the MIL will be illuminated during step (h).

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

    NEXT: OK GO TO NEXT STEP 

  16. CHECK WHETHER DTC OUTPUT RECURS ( DTC P0171, P0172: SYSTEM TOO LEAN/RICH (BANK 1)  ) 
    1. On the hand-held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
    2. Read DTCs.

      Result: 

      DTC OUTPUT RESULT

      Display (DTC Output) Proceed To
      No output A
      P0171 or P0172 B
    1. B: Go to step   5 
    2. A: OK GO TO NEXT STEP 

      END 

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