SFI SYSTEM, Diagnostic DTC:P0136, P0137, P0138, P0156, P0157, P0158

DESCRIPTION

A three-way catalyst converter is used in order to convert the carbon monoxide, hydrocarbons and nitrogen oxide into less harmful substances. To allow the three-way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the stoichiometric air fuel ratio. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used.

The heated oxygen sensor is located behind the three-way catalytic converter, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).

When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is rich. The heated oxygen sensor informs the ECM that the post-three way catalytic converter air fuel ratio is lean (low voltage, i.e. below 0.45 V).

Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas becomes lean. The heated oxygen sensor informs the ECM that the post-three way catalytic converter air fuel ratio is rich (high voltage, i.e. higher than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.

The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the three-way catalytic converter is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.

MONITOR DESCRIPTION

• Active Air-fuel Ratio Control

  The ECM usually performs air-fuel ratio feedback control so that the air fuel ratio sensor output indicates a near stoichiometric air-fuel ratio. This vehicle includes active air-fuel ratio control in addition to regular air-fuel ratio control. The ECM performs active air-fuel ratio control to detect any deterioration in the Three-way Catalytic Converter (TWC) and heated oxygen sensor malfunctions (refer to the diagram below).

  Active air-fuel ratio control is performed for approximately 15 to 20 seconds while driving with a warm engine. During active air-fuel ratio control, the air-fuel ratio is forcibly regulated to become lean or rich by the ECM. If the ECM detects a malfunction, a DTC is stored.

• Abnormal Voltage Output of Heated Oxygen Sensor (DTC P0136 and P0156)

  While the ECM is performing active air-fuel ratio control, the air-fuel ratio is forcibly regulated to become rich or lean. If the sensor is not functioning properly, the voltage output variation is small. For example, when the heated oxygen sensor voltage does not decrease to below 0.21 V and does not increase to higher than 0.66 V during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormal and stores DTC P0136 or P0156.

  

• Open or Short in Heated Oxygen Sensor Circuit (DTC P0137 and P0157 or P0138 and P0158)

  During active air-fuel ratio control, the ECM calculates the Oxygen Storage Capacity (OSC)* of the Three-way Catalytic Converter (TWC) by forcibly regulating the air-fuel ratio to become rich or lean. If the heated oxygen sensor has an open or short, or the voltage output of the sensor decreases significantly, the Oxygen Storage Capacity (OSC) is indicated as having an extraordinarily high value. Even if the ECM attempts to continue regulating the air-fuel ratio to become rich or lean, the heated oxygen sensor output does not change.

  While performing active air-fuel ratio control, when the target air-fuel ratio is rich and the HO2 sensor voltage output is 0.21 V or less (lean), the ECM interprets this as an abnormally low sensor output voltage and stores DTC P0137 or P0157. When the target air-fuel ratio is lean and the voltage output is 0.66 V or more (rich) during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormally high and stores DTC P0138 or P0158.

  *: The Three-way Catalytic Converter (TWC) has the capability to store oxygen. The Oxygen Storage Capacity (OSC) and the emissions purification capacity of the Three-way Catalytic Converter (TWC) are mutually related. The ECM determines whether the catalyst has deteriorated based on the calculated Oxygen Storage Capacity (OSC) value Click here.

  

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

1. Connect the GTS to the DLC3.

2. Clear the DTCs.

3. Turn the ignition switch off.

4. Turn the ignition switch to ON and turn the GTS on (Step "A").

5. Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more (Step "B").

6. With the transmission in 4th gear or more, drive the vehicle at 60 to 120 km/h (37 to 75 mph) for 10 minutes or more (Step "C").

7. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

8. Input DTCs: P0136, P0137, P0138, P0156, P0157 and P0158.

9. Check the DTC judgment result (Step "D").

   GTS Display	Description
   NORMAL	DTC judgment completed System normal
   ABNORMAL	DTC judgment completed System abnormal
   INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
   N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

   CAUTION:

   When performing the confirmation driving pattern, obey all speed limits and traffic laws.

10. Check that STATUS is NORMAL. If STATUS is INCOMPLETE or N/A, perform the driving pattern adding the vehicle speed and using the second gear to decelerate the vehicle.

CAUTION / NOTICE / HINT

• Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio sensor and heated oxygen sensors.

• To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.

PROCEDURE

1. READ OUTPUT DTC (DTC P0136, P0137, P0138, P0156, P0157 OR P0158)

   
   

   1. Connect an GTS to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

   5. Read DTCs.

      Result

      Result	Proceed to
      P0138 or P0158	A
      P0137 or P0157	B
      P0136 or P0156	C
      P0136, P0137, P0138, P0156, P0157 or P0158 and other DTCs are output	D

   
   

   B

   CHECK FOR EXHAUST GAS LEAK Click here

   C

   PERFORM ACTIVE TEST USING GTS (INJECTION VOLUME) Click here

   D

   GO TO DTC CHART Click here

   A

2. READ VALUE USING GTS (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)

   
   

   1. Connect an GTS to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Enter the following menus: Powertrain / Engine and ECT / Data List / O2S B1S2 or O2S B2S2.

   5. Allow the engine to idle.

   6. Read the heated oxygen sensor output voltage while idling.

      Result

      Result	Proceed to
      Higher than 1.0 V	A
      Below 1.0 V	B

   
   

   B

   PERFORM ACTIVE TEST USING GTS (INJECTION VOLUME) Click here

   A

3. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)

   
   
   1. 

      Text in Illustration

      *A	for Bank 1
      *B	for Bank 2
      *a	Component without harness connected (Heated Oxygen Sensor)

      Disconnect the heated oxygen sensor connector.

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

      Standard Resistance (Bank 1 Sensor 2)
      Tester Connection Condition Specified Condition 2 (+B) - 4 (E2) 20°C (68°F) 10 kΩ or higher 2 (+B) - 3 (OX1B) Always 10 kΩ or higher

      Standard Resistance (Bank 2 Sensor 2)
      Tester Connection Condition Specified Condition 2 (+B) - 4 (E2) 20°C (68°F) 10 kΩ or higher 2 (+B) - 3 (OX2B) Always 10 kΩ or higher

   3. Reconnect the heated oxygen sensor connector.

   
   

   NG

   REPLACE HEATED OXYGEN SENSOR Click here

   OK

4. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

   
   

   1. Disconnect the heated oxygen sensor connector.

   2. Disconnect the ECM connector.

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

      Standard Resistance
      for LHD Tester Connection Condition Specified Condition C45-45 (HT1B) - C45-114 (OX1B) Always 10 kΩ or higher C45-44 (HT2B) - C45-112 (OX2B) Always 10 kΩ or higher
      for RHD Tester Connection Condition Specified Condition C46-45 (HT1B) - C46-114 (OX1B) Always 10 kΩ or higher C46-44 (HT2B) - C46-112 (OX2B) Always 10 kΩ or higher

   4. Reconnect the heated oxygen sensor connector.

   5. Reconnect the ECM connector.

   
   

   OK

   REPLACE ECM Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - HEATED OXYGEN SENSOR)

5. PERFORM ACTIVE TEST USING GTS (INJECTION VOLUME)

   
   

   1. Connect the GTS to the DLC3.

   2. Start the engine.

   3. Turn the GTS on.

   4. Warm up the engine.

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

   6. Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio sensor and heated oxygen sensor displayed on the GTS.

      Tech Tips

      
      

      • Change the fuel injection volume within the range of -12.5% to +12.5%.

      • The air fuel ratio sensor is displayed as AFS Voltage B1S1 or AFS Voltage B2S1, and the heated oxygen sensor is displayed as O2S B1S2 or O2S B2S2 on the GTS.

      Result

      GTS Display (Sensor)	Voltage Variation	Proceed to
      AFS Voltage B1S1 AFS Voltage B2S1 (Air fuel ratio sensor)	Alternates between higher than and below 3.3 V	OK
      	Remains at higher than 3.3 V	NG
      	Remains at below 3.3 V	NG

      Tech Tips

      A normal heated oxygen sensor voltage (O2S B1S2 or O2S B2S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage remains at either below or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

      

   
   

   NG

   REPLACE AIR FUEL RATIO SENSOR Click here

   OK

6. CHECK AIR FUEL RATIO SENSOR

   Tech Tips

   This air fuel ratio sensor test is to check the air fuel ratio sensor current during the fuel-cut operation. When the sensor is normal, the sensor current will be below 3 mA in this test.

   
   

   1. Connect an GTS to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Clear.

   5. Clear DTCs.

   6. Drive the vehicle according to the driving pattern listed below:

      
      

      1. Warm up the engine.

      2. Drive the vehicle at 60 km/h (40 mph) or more for 10 minutes or more.

      3. Stop the vehicle.

      4. Accelerate the vehicle to 60 km/h (40 mph) or more and then decelerate for 5 seconds or more. Repeat this process at least 3 times.

         

         Driving Pattern

         *a	60 km/h (40 mph)
         *b	0 km/h (0 mph)
         *c	10 minutes or more
         *d	5 seconds or more

   7. Enter the following menus: Powertrain / Engine and ECT / Data List / AFS Current B1S1 and AFS Current B2S1.

   8. Read the value of the air fuel ratio sensor current while the fuel-cut operation is being performed.

      Standard current
      Below 2.2 mA

      Tech Tips

      
      

      • To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.

      • If it is difficult to measure the air fuel ratio sensor current, use the snapshot function of the GTS.

      Result

      Result	Proceed to
      Outside standard range	A
      Within standard range	B

   
   

   A

   REPLACE AIR FUEL RATIO SENSOR Click here

   B

   REPLACE HEATED OXYGEN SENSOR Click here

7. PERFORM ACTIVE TEST USING GTS (INJECTION VOLUME)

   
   

   1. Connect the GTS to the DLC3.

   2. Start the engine.

   3. Turn the GTS on.

   4. Warm up the engine.

   5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / O2S B1S2 or O2S B2S2.

   6. Change the fuel injection volume using the GTS, monitoring the voltage output of the heated oxygen sensor displayed on the GTS.

      Tech Tips

      
      

      • Change the fuel injection volume within the range of - 12.5% to +12.5%.

      • 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.

      Standard voltage
      Fluctuates between 0.4 V or less and 0.55 V or higher.

   
   

   NG

   CHECK FOR EXHAUST GAS LEAK Click here

   OK

8. PERFORM ACTIVE TEST USING GTS (INJECTION VOLUME)

   
   

   1. Connect the GTS to the DLC3.

   2. Start the engine.

   3. Turn the GTS on.

   4. Warm up the engine.

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

   6. Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio sensor and heated oxygen sensor displayed on the GTS.

      Tech Tips

      
      

      • Change the fuel injection volume within the range of -12.5% to +12.5%.

      • The air fuel ratio sensor is displayed as AFS Voltage B1S1 or AFS Voltage B2S1, and the heated oxygen sensor is displayed as O2S B1S2 or O2S B2S2 on the GTS.

      Result

      GTS Display (Sensor)	Voltage Variation	Proceed to
      AFS Voltage B1S1 AFS Voltage B2S1 (Air fuel ratio sensor)	Alternates between higher than and below 3.3 V	OK
      	Remains at higher than 3.3 V	NG
      	Remains at below 3.3 V	NG

      Tech Tips

      A normal heated oxygen sensor voltage (O2S B1S2 or O2S B2S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage remains at either below or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

      

   
   

   OK

   CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (FUEL INJECTOR, FUEL PRESSURE, GAS LEAK FROM SYSTEM, ETC.)

   NG

   REPLACE AIR FUEL RATIO SENSOR Click here

9. CHECK FOR EXHAUST GAS LEAK

   
   

   1. Check for exhaust gas leakage.

      OK
      No gas leak.

   
   

   NG

   REPAIR OR REPLACE EXHAUST GAS LEAK POINT

   OK

10. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

    
    

    1. Inspect the heated oxygen sensor Click here.

    
    

    NG

    REPLACE HEATED OXYGEN SENSOR Click here

    OK

11. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

    
    

    1. Disconnect the heated oxygen sensor connector.

    2. Disconnect the ECM connector.

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

       Standard Resistance
       for LHD Tester Connection Condition Specified Condition C20-1 (HT1B) - C45-45 (HT1B) Always Below 1 Ω C20-3 (OX1B) - C45-114 (OX1B) Always Below 1 Ω C20-4 (E2) - C45-115 (EX1B) Always Below 1 Ω C21-1 (HT2B) - C45-44 (HT2B) Always Below 1 Ω C21-3 (OX2B) - C45-112 (OX2B) Always Below 1 Ω C21-4 (E2) - C45-113 (EX2B) Always Below 1 Ω C20-1 (HT1B) or C45-45 (HT1B) - Body ground Always 10 kΩ or higher C20-3 (OX1B) or C45-114 (OX1B) - Body ground Always 10 kΩ or higher C20-4 (E2) or C45-115 (EX1B) - Body ground Always 10 kΩ or higher C21-1 (HT2B) or C45-44 (HT2B) - Body ground Always 10 kΩ or higher C21-3 (OX2B) or C45-112 (OX2B) - Body ground Always 10 kΩ or higher C21-4 (E2) or C45-113 (EX2B) - Body ground Always 10 kΩ or higher
       for RHD Tester Connection Condition Specified Condition C20-1 (HT1B) - C46-45 (HT1B) Always Below 1 Ω C20-3 (OX1B) - C46-114 (OX1B) Always Below 1 Ω C20-4 (E2) - C46-115 (EX1B) Always Below 1 Ω C21-1 (HT2B) - C46-44 (HT2B) Always Below 1 Ω C21-3 (OX2B) - C46-112 (OX2B) Always Below 1 Ω C21-4 (E2) - C46-113 (EX2B) Always Below 1 Ω C20-1 (HT1B) or C46-45 (HT1B) - Body ground Always 10 kΩ or higher C20-3 (OX1B) or C46-114 (OX1B) - Body ground Always 10 kΩ or higher C20-4 (E2) or C46-115 (EX1B) - Body ground Always 10 kΩ or higher C21-1 (HT2B) or C46-44 (HT2B) - Body ground Always 10 kΩ or higher C21-3 (OX2B) or C46-112 (OX2B) - Body ground Always 10 kΩ or higher C21-4 (E2) or C46-113 (EX2B) - Body ground Always 10 kΩ or higher

       

    4. Reconnect the heated oxygen sensor connector.

    5. Reconnect the ECM connector.

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - HEATED OXYGEN SENSOR)

    OK

12. REPLACE HEATED OXYGEN SENSOR

    
    

    1. Replace the heated oxygen sensor Click here.

    
    

    NEXT

13. PERFORM CONFIRMATION DRIVING PATTERN

    Tech Tips

    Refer to Confirmation Driving Pattern.

    
    

    NEXT

14. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137, P0138, P0156, P0157 OR P0158)

    
    

    1. Connect an GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

    5. Input DTCs: P0136, P0137, P0138, P0156, P0157 and P0158.

    6. Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again by accelerating the vehicle and using the second gear to decelerate the vehicle.

       Result

       Result	Proceed to
       NORMAL (No DTC output)	A
       ABNORMAL (P0136, P0137, P0138, P0156, P0157 or P0158 stored)	B

    
    

    A

    END

    B

    REPLACE AIR FUEL RATIO SENSOR Click here

15. REPLACE AIR FUEL RATIO SENSOR

    
    

    1. Replace the air fuel ratio sensor Click here.

    
    

    NEXT

16. PERFORM CONFIRMATION DRIVING PATTERN

    Tech Tips

    Refer to Confirmation Driving Pattern.

    
    

    NEXT

17. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137, P0138, P0156, P0157 OR P0158)

    
    

    1. Connect an GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

    5. Input DTCs: P0136, P0137, P0138, P0156, P0157 and P0158.

    6. Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again by accelerating the vehicle and using the second gear to decelerate the vehicle.

       Result

       Result	Proceed to
       NORMAL (No DTC output)	A
       ABNORMAL (P0136, P0137, P0138, P0156, P0157 or P0158 stored)	B

    
    

    A

    END

    B

    REPLACE HEATED OXYGEN SENSOR Click here