Inspection Procedure

HINT:

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 (A/F) sensor, Heated Oxygen (HO2) 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 a Techstream.

1. Connect the Techstream to the DLC3.
2. Start the engine.
3. Turn the tester ON.
4. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
6. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume.)
7. Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.

HINT:

• 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.
  VOLTAGE SPECIFICATION
  
  

  Tester Display (Sensor)	Injection Volume	Status	Voltage
  AFS B1 S1 (A/F)	+25%	Rich	Less than 3.0 V
  	-12.5%	Lean	More than 3.35 V
  O2S B1 S2 (HO2)	+25%	Rich	More than 0.55 V
  	-12.5%	Lean	Less than 0.4 V

  NOTE: The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.
  AIR-FUEL RATIO OUTPUT VOLTAGE CHART
  
  

  Case	A/F Sensor (Sensor 1) Output Voltage	HO2 Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
  1	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
  2	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	A/F sensor A/F sensor heater A/F sensor circuit
  3	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	HO2 sensor HO2 sensor heater HO2 sensor circuit
  4	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injector Fuel pressure Gas leak from exhaust system (Air-fuel ratio extremely rich or lean)

• Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
• To display the graph, select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 and O2S B1 S2; then press the graph button on the Data List view.

HINT:

• Read freeze frame data using the Techstream. 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 A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
• A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run lean.

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195 OR P2196) 
   1. Connect a Techstream to the DLC3.
   2. Turn the ignition switch to ON.
   3. Turn the tester ON.
   4. Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
   5. Read DTCs.

      Result 

      RESULT CHART
      
      

      Display (DTC Output)	Proceed To
      P2195 or P2196	A
      P2195 or P2196 and other DTCs	B

      HINT:

      If any DTCs relating to the A/F sensor (DTCs for the A/F sensor heater or A/F sensor admittance) are output, troubleshoot those DTCs first.

   B: GO TO DTC CHART (See  DIAGNOSTIC TROUBLE CODE CHART   ) 

   A: Go to Next Step 

2. READ VALUE USING TECHSTREAM (TEST VALUE OF A/F SENSOR) 
   1. Connect the Techstream to the DLC3.
   2. Turn the ignition switch to ON.
   3. Turn the tester ON.
   4. Clear DTCs (See DTC CHECK/CLEAR  ).
   5. Drive the vehicle in accordance with the drive pattern described in the CONFIRMATION DRIVING PATTERN.
   6. Select the following menu items: Powertrain / Engine and ECT / Monitor / O2 Sensor.
   7. Check that the status of O2 Sensor is Complete. If the status is still Incomplete, perform the drive pattern increasing the vehicle speed and using the second gear to decelerate the vehicle.
   8. Select the following menu items: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details / RANGE B1 S1.
   9. Check the test value of the A/F sensor output current during fuel cut.

      Result 

      RESULT CHART
      
      

      Test Value	Proceed To
      Within normal range (1.0 mA or more, and less than 3.6 mA)	A
      Outside normal range (Less than 1.0 mA, or 3.6 mA or more)	B

   B:  Go to step  12

   A: Go to Next Step 

3. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR) 
   1. Connect the Techstream to the DLC3.
   2. Start the engine.
   3. Turn the tester ON.
   4. Warm up the A/F sensor at an engine speed of 2,500 rpm for 90 seconds.
   5. Select the following menu items: Powertrain / Engine and ECT / Data List / A/F Control System / AFS B1 S1 and Engine Speed, then press the Record button.
   6. Check the A/F sensor voltage three times, when the engine is in each of the following conditions:
      1. While idling (check for at least 30 seconds)
      2. At an engine speed of approximately 2,500 rpm (without any sudden changes in engine speed)
      3. Raise the engine speed to 4,000 rpm and then quickly release the accelerator pedal so that the throttle valve is fully closed.

         Standard voltage 

         VOLTAGE SPECIFICATION
         
         

         Conditions	A/F Sensor Voltage Variations	Reference
         (1) and (2)	Remains at approximately 3.3 V	Between 3.1 V and 3.5 V
         (3)	Increases to 3.8 V or more	This occurs during engine deceleration (when fuel cut performed)

         HINT:

         • For more information, see the diagrams below.
           Fig 1: A/F Sensor Normal And Malfunction Condition Chart

           Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
         • If the output voltage of the A/F sensor remains at approximately 3.3 V (see Malfunction Condition diagram ) under any conditions, including those above, the A/F sensor may have an open circuit. (This will also happen if the A/F sensor heater has an open circuit.)
         • If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Malfunction Condition diagram ) under any conditions, including those above, the A/F sensor may have a short circuit.
         • The ECM stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and result in a momentary increase in the A/F sensor output voltage.
         • The ECM must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM to learn the closed throttle valve position.
         • When the vehicle is driven:

           The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. For the vehicle, this translates to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.

         • The A/F sensor is a current output element; therefore, the current is converted into a voltage inside the ECM.

           Measuring the voltage at the connectors of the A/F sensor or ECM will show a constant voltage result.

   NG:  Go to step  9

   OK: Go to Next Step 

4. PERFORM CONFIRMATION DRIVING PATTERN 
5. CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196) 
   1. Connect the Techstream to the DLC3.
   2. Turn the ignition switch to ON.
   3. Turn the tester ON.
   4. Select the following menu items: Powertrain / Engine and ECT / Trouble Codes / Pending.

      Result 

      RESULT CHART
      
      

      Display (DTC Output)	Proceed To
      P2195 or P2196	A
      No output	B

   B: END 

   A: Go to Next Step 

6. REPLACE AIR-FUEL RATIO SENSOR 
   1. Replace the A/F sensor (See REMOVAL ).
7. PERFORM CONFIRMATION DRIVING PATTERN 
8. CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196) 
   1. Connect the Techstream to the DLC3.
   2. Turn the ignition switch to ON.
   3. Turn the tester ON.
   4. Select the following menu items: Powertrain / Engine and ECT / Trouble Codes / Pending.

      Result 

      RESULT CHART
      
      

      Display (DTC Output)	Proceed To
      No output	A
      P2195 or P2196	B

   B: REPLACE ECM (See  REMOVAL   ) 

   A: END 

9. INSPECT AIR-FUEL RATIO SENSOR (HEATER RESISTANCE) (See  INSPECTION PROCEDURE   ) 

   NG: REPLACE AIR-FUEL RATIO SENSOR  (See REMOVAL )

   OK: Go to Next Step 

10. INSPECT INTEGRATION RELAY (EFI RELAY) (See  INSPECTION PROCEDURE   ) 

    NG: REPLACE INTEGRATION RELAY (EFI RELAY) (See  REMOVAL   ) 

    OK: Go to Next Step 

11. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) 
    Fig 2: Identifying Harness And Connector (A/F Sensor - ECM)

    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the C23 A/F sensor connector.
    2. Turn the ignition switch to ON.
    3. Check the voltage between the +B terminal of the A/F sensor connector and body ground.

       Standard voltage 

       TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
       
       

       Tester Connections	Specified Conditions
       +B (C23-2) - Body ground	11 to 14 V

    4. Turn the ignition switch to OFF.
    5. Disconnect the C20 ECM connector.
    6. Check the resistance.

       Standard resistance (Check for open) 

       TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
       
       

       Tester Connections	Specified Conditions
       HA1A (C23-1) - HA1A (C20-109)	Below 1 Ω
       A1A+ (C23-3) - A1A+ (C20-112)
       A1A- (C23-4) - A1A- (C20-113)

       Standard resistance (Check for short) 

       TESTER CONNECTIONS SPECIFIED CONDITIONS CHART
       
       

       Tester Connections	Specified Conditions
       HA1A (C23-1) or HA1A (C20-109) - Body ground	10 kΩ or higher
       A1A+ (C23-3) or A1A+ (C20-112) - Body ground
       A1A- (C23-4) or A1A- (C20-113) - Body ground

    7. Reconnect the ECM connector.
    8. Reconnect the A/F sensor connector.
       Fig 3: Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) Circuit Diagram

       Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to Next Step 

12. REPLACE AIR-FUEL RATIO SENSOR 
    1. Replace the A/F sensor (See REMOVAL ).
13. PERFORM CONFIRMATION DRIVING PATTERN 
14. CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the tester ON.
    4. Select the following menu items: Powertrain / Engine and ECT / Trouble Codes / Pending.

       Result 

       RESULT CHART
       
       

       Display (DTC Output)	Proceed To
       No output	A
       P2195 or P2196	B

    B: REPLACE ECM (See  REMOVAL   ) 

    A: END