SFI SYSTEM (w/ Secondary Air Injection System), Diagnostic DTC:P2195, P2196

DESCRIPTION

The A/F sensor generates a voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.

The A/F sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate air-fuel ratio detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

*: Value changes inside the ECM. Since the A/F sensor is the current output element, a current is converted to a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.

MONITOR DESCRIPTION

Sensor voltage detection monitor

Under the air-fuel ratio feedback control, if the A/F sensor voltage output indicates rich or lean for a certain period of time, the ECM determines that there is a malfunction in the A/F sensor. The ECM illuminates the MIL and sets a DTC.

Example:

If the A/F sensor voltage output is less than 2.8 V (very rich condition) for 10 seconds, despite the HO2 sensor voltage output being less than 0.60 V, the ECM sets DTC P2196. Alternatively, if the A/F sensor voltage output is more than 3.8 V (very lean condition) for 10 seconds, despite the rear HO2 sensor voltage output being 0.15 V or more, DTC P2195 is set.

Sensor current detection monitor

A rich air-fuel mixture causes a low A/F sensor current, and a lean air-fuel mixture causes a high A/F sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration with the throttle valve fully closed. The ECM monitors the A/F sensor current during fuel-cut and detects any abnormal current values.

If the A/F sensor output is 3.6 mA or more for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the A/F sensor and sets DTC P2195 (high-side stuck). If the A/F sensor output is 1.0 mA or less for more than 3 seconds of cumulative time, the ECM sets DTC P2196 (low-side stuck).

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

This confirmation driving pattern is used in steps 10, 13 and 16 of the following diagnostic troubleshooting procedure when using an intelligent tester.

1. Connect an intelligent tester to the DLC3.

2. Turn the ignition switch to the ON position.

3. Turn the tester ON.

4. Clear DTCs Click here.

5. Start the engine, and warm it up until the ECT reaches 70°C (158°F) or higher (1).

6. On the intelligent tester, select the following menu items to check the fuel-cut status: Powertrain / Engine and ECT / Data List / Idle Fuel Cut.

7. Drive the vehicle at between 60 km/h (38 mph) and 120 km/h (75 mph) for at least 10 minutes (2).

8. Change the transmission gear selector lever to the 2nd position.

9. Drive the vehicle at proper vehicle speed to perform fuel-cut operation.

   Tech Tips

   
   

   • Fuel-cut is performed when the following conditions are met:

   
   

   • Accelerator pedal is fully released.

   • Engine speed is 2,500 rpm or more (fuel injection with engine speed at 1,000 rpm is restored).

10. Accelerate the vehicle to 64 km/h (40 mph) or more by depressing the accelerator pedal for at least 10 seconds (3).

11. Soon after performing step (j) above, release the accelerator pedal for at least 4 seconds without depressing the brake pedal, in order to execute fuel-cut control (4).

12. Allow the vehicle to decelerate until the vehicle speed declines to less than 10 km/h (6 mph) (5).

13. Repeat steps from (3) through (5) above at least 3 times in one driving cycle.

INSPECTION PROCEDURE

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

1. Connect an intelligent 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: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.

5. Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

6. Monitor the voltage outputs of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the tester.

Voltage
Tester Display (Sensor) Injection Volumes Status Voltages AFS Voltage B1S1 (A/F) +25 % Rich Less than 3.1 AFS Voltage B1S1 (A/F) -12.5 % Lean More than 3.4 O2S B1S2 (HO2) +25 % Rich More than 0.5 O2S B1S2 (HO2) -12.5 % Lean Less than 0.4

• 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 on the tester: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / User Data / AFS Voltage B1S1 and O2S B1S2.

PROCEDURE

1. CHECK OTHER DTC OUTPUT (BESIDE A/F SENSOR DTC)

   
   

   1. Connect an intelligent tester to the DLC3.

   2. Turn the ignition switch to the ON position.

   3. Turn the tester ON.

   4. Select the following menu items: Powertrain / Engine and ECT / DTC.

   5. Read DTCs.

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

      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

   A

2. READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF A/F SENSOR)

   
   

   1. Connect the Intelligent Tester to the DLC3.

   2. Warm up the A/F sensor at 2,500 rpm for approximately 90 seconds.

   3. Read A/F sensor voltage output on the intelligent tester.

   4. Select "Powertrain / Engine and ECT / Data List / AFS Voltage B1S1 and Engine Spd.

   5. Monitor the A/F sensor voltage carefully.

   6. Check the A/F sensor voltage under the condition as follows:

      
      

      1. Allow engine to idle for 30 seconds.

      2. Engine is racing at approx. 2,500 rpm (when engine revolution is not suddenly changed).

      3. Raise the engine speed to 4,000 rpm and release the fully closed accelerator pedal quickly.

         Standard
         Condition (1) and (2)
         Voltage changes in the vicinity of 3.3 V (0.66 V)* (between approx. 3.1 to 3.5 V) as shown in the illustration.
         Condition (3)
         A/F sensor voltage increases to 3.8 V (0.76 V)* or more during engine deceleration (when fuel cut) as shown in the illustration.

         

         Tech Tips

         
         

         • Whenever the output voltage of the A/F sensor remains at approx. 3.3 V (0.66 V)* (see Malfunction Condition Diagram) under any condition as well as the above conditions, the A/F sensor may have an open-circuit. (This will happen also when the A/F sensor heater has an open-circuit.).

         • Whenever the output voltage of the A/F sensor remains at a certain value of approx. 3.8 V (0.76 V)* or more, or 2.8 V (0.56 V)* or less (see Malfunction Condition Diagram) under any condition as well as the above conditions, the A/F sensor may have a short-circuit.

         • The ECM will stop fuel injection (fuel cut) during engine deceleration. This will cause a lean condition and should result in a momentary increase in A/F sensor voltage output.

         • When the vehicle is driven: In the case that the output voltage of the A/F sensor is below 2.8 V (0.76 V)* during fuel enrichment (for example, when the vehicle tries to overtake another vehicle on a highway, the vehicle speed is suddenly increased with the accelerator pedal fully depressed), the A/F sensor is functioning normally.

         • The A/F sensor is a current output element, and therefore the current is converted into voltage inside the ECM. If measuring voltage at connectors of the A/F sensor or ECM, you will obtain a constant voltage.

         *: When not using the intelligent tester.

   
   

   OK

   PERFORM CONFIRMATION DRIVING PATTERN Click here

   NG

3. INSPECT AIR FUEL RATIO SENSOR

   
   

   1. 

      Disconnect the D33 Air-Fuel Ratio (A/F) sensor connector.

   2. Measure the resistance between the terminals of the A/F sensor connector.

      Resistance
      Tester Connections Specified Conditions HA1A (1) - +B (2) 1.8 Ω to 3.4 Ω at 20 °C (68°F) HA1A (1) - A1A- (4) 10 kΩ or higher

   3. Reconnect the A/F sensor connector.

   
   

   NG

   REPLACE AIR FUEL RATIO SENSOR

   OK

4. INSPECT INTEGRATION NO.1 RELAY (A/F HEATER RELAY)

   
   

   1. Remove the integration relay from the engine room R/B No.1.

   2. 

      Check the integration relay (A/F HEATER relay).

      Resistance
      Tester Connections Specified Conditions A1 - C4 10 kΩ or higher A1 - C4 Below 1 Ω (when battery voltage applied to terminals C2 and C3)

   3. Reinstall the integration relay.

   
   

   NG

   REPLACE INTEGRATION NO.1 RELAY

   OK

5. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM)

   
   

   1. 

      Disconnect the D33 air-fuel ratio sensor connector.

   2. Turn the ignition switch to the ON position.

   3. Measure the voltage between the +B terminal of the air-fuel ratio sensor connector and body ground.

      Voltage
      Tester Connections Specified Conditions +B (D33-2) - Body ground 9 to 14 V

   4. Turn the ignition switch to OFF.

   5. Disconnect the D1 ECM connector.

   6. Measure the resistance.

      Resistance (Check for open)
      Tester Connections Specified Conditions HA1A (D33-1) - HA1A (D1-1) Below 1 Ω A1A+ (D33-3) - A1A+ (D1-21) Below 1 Ω A1A- (D33-4) - A1A- (D1-31) Below 1 Ω

      Resistance (Check for short)
      Tester Connections Specified Conditions HA1A (D33-1) or HA1A (D1-1) - Body ground 10 kΩ or higher A1A+ (D33-3) or A1A+ (D1-21) - Body ground 10 kΩ or higher A1A- (D33-4) or A1A- (D1-31) - Body ground 10 kΩ or higher

   7. Reconnect the ECM connector.

   8. Reconnect the air-fuel ratio sensor connector.

      

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

6. CHECK AIR INDUCTION SYSTEM

   
   

   1. Check for vacuum leaks in the air induction system.

      OK
      No leakage from air induction system.

   
   

   NG

   REPAIR OR REPLACE AIR INDUCTION SYSTEM

   OK

7. CHECK FUEL PRESSURE

   
   

   1. Check fuel pressure (High or low fuel pressure).

   
   

   NG

   REPAIR OR REPLACE FUEL SYSTEM

   OK

8. INSPECT FUEL INJECTION ASSEMBLY

   
   

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

   
   

   NG

   REPLACE FUEL INJECTOR ASSEMBLY

   OK

9. REPLACE AIR FUEL RATIO SENSOR

   
   

   NEXT

10. PERFORM CONFIRMATION DRIVING PATTERN

    Tech Tips

    Clear all DTCs prior to perform the confirmation driving pattern.

    
    

    NEXT

11. READ OUTPUT DTC (A/F SENSOR DTC OUTPUT AGAIN)

    
    

    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn the intelligent tester ON.

    4. On the intelligent tester, select the following items: Powertrain / Engine and ECT / DTC.

    5. Read DTCs.

       Result
       Display Proceed To No output A P2195 or P2196 B

    
    

    B

    REPLACE ECM

    A

12. CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST

    
    

    NO

    CHECK FOR INTERMITTENT PROBLEMS

    YES

    DTC IS CAUSED BY RUNNING OUT OF FUEL

13. PERFORM CONFIRMATION DRIVING PATTERN

    Tech Tips

    Clear all DTCs prior to perform the confirmation driving pattern.

    
    

    NEXT

14. READ OUTPUT DTC (A/F SENSOR DTC OUTPUT AGAIN)

    
    

    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn the intelligent tester ON.

    4. On the intelligent tester, select the following items: Powertrain / Engine and ECT / DTC.

    5. Read DTCs.

       Result
       Display Proceed To No output A P2195 or P2196 B

    
    

    B

    CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST Click here

    A

15. REPLACE AIR FUEL RATIO SENSOR

    
    

    NEXT

16. PERFORM CONFIRMATION DRIVING PATTERN

    Tech Tips

    Clear all DTCs prior to perform the confirmation driving pattern.

    
    

    NEXT

17. READ OUTPUT DTC (A/F SENSOR DTC OUTPUT AGAIN)

    
    

    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn the intelligent tester ON.

    4. On the intelligent tester, select the following items: Powertrain / Engine and ECT / DTC.

    5. Read DTCs.

       Result
       Display Proceed To No output A P2195 or P2196 B

    
    

    B

    REPLACE ECM

    A

18. CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST

    
    

    NO

    CHECK FOR INTERMITTENT PROBLEMS

    YES

    DTC IS CAUSED BY RUNNING OUT OF FUEL