SFI SYSTEM, Diagnostic DTC:P0031, P0032, P0051, P0052, P101D, P103D

DESCRIPTION

The air fuel ratio sensor generates 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 air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is the planar type and is integrated with a 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 oxygen concentration 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), hydrocarbons (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three way catalytic converter is used. For the most efficient use of the three way catalytic converter, 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 air fuel ratio sensor is a current output element, the current is converted to a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

MONITOR DESCRIPTION

• The ECM uses information from the air fuel ratio sensor to regulate the air fuel ratio and keep it close to the stoichiometric level. This maximizes the ability of the three way catalytic converter to purify the exhaust gases.

• The air fuel ratio sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum coated zirconia and includes an integrated heating element.

• The zirconia element generates a small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.

• The air fuel ratio sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful voltage signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the air fuel ratio sensor will be inaccurate, as a result, the ECM will be unable to regulate air fuel ratio properly.

• When the current in the air fuel ratio sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and sets a DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

CONFIRMATION DRIVING PATTERN

1. Connect the GTS to the DLC3.

2. Turn the power switch on (IG) and turn the GTS on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.

4. Turn the power switch off and wait for 30 seconds.

5. Turn the power switch on (IG) and turn the GTS on [A].

6. Put the engine in inspection mode (maintenance mode) Click here.

7. Start the engine and idle it for 5 minutes or more [B].

8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].

   Tech Tips

   During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, perform steps [C] and [D] after charging control has completed.

9. Idle the engine for 5 minutes or more [D].

10. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].

11. Read Pending DTCs.

    Tech Tips

    
    

    • If a pending DTC is not output, perform the following procedure.

    • If a pending DTC is output, the system is malfunctioning.

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

13. Input the DTC: P0031, P0032, P0051, P0052, P101D or P103D.

14. Check the DTC judgment result.

    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's memory limit

    Tech Tips

    
    

    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [E] again.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

CAUTION / NOTICE / HINT

PROCEDURE

1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

   
   

   1. Inspect the air fuel ratio sensor Click here.

      Tech Tips

      Perform "Inspection After Repair" after replacing the air fuel ratio sensor Click here.

   
   

   NG

   REPLACE AIR FUEL RATIO SENSOR Click here

   OK

2. CHECK TERMINAL VOLTAGE (+B OF AIR FUEL RATIO SENSOR)

   
   
   1. 

      Text in Illustration

      *1	Bank 1
      *2	Bank 2
      *a	Front view of wire harness connector (to Air Fuel Ratio Sensor)

      Disconnect the air fuel ratio sensor connector.

   2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition F62-2 (+B) - Body ground Power switch on (IG) 11 to 14 V F86-2 (+B) - Body ground Power switch on (IG) 11 to 14 V

   4. Reconnect the air fuel ratio sensor connector.

   
   

   NG

   CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY) Click here

   OK

3. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

   
   

   1. Disconnect the air fuel ratio sensor connector.

   2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition F62-1 (HA1A) - F5-26 (HA1A) Always Below 1 Ω F86-1 (HA2A) - F5-20 (HA2A) Always Below 1 Ω F62-1 (HA1A) or F5-26 (HA1A) - Body ground Always 10 kΩ or higher F86-1 (HA2A) or F5-20 (HA2A) - Body ground Always 10 kΩ or higher

   4. Reconnect the air fuel ratio sensor connector.

   5. Reconnect the ECM connector.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

   OK

4. CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032, P0051, P0052, P101D OR P103D)

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the power switch on (IG).

   3. Turn the GTS on.

   4. Clear the DTCs Click here.

   5. Turn the power switch off and wait for at least 30 seconds.

   6. Turn the power switch on (IG).

   7. Turn the GTS on.

   8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

   9. Read the output pending DTCs using the GTS.

      Result
      Result Proceed to Pending DTC is not output A Pending DTC P0031, P0032, P0051, P0052, P101D or P103D is output B

   
   

   A

   CHECK FOR INTERMITTENT PROBLEMS Click here

   B

   REPLACE ECM Click here

5. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY)

   
   

   1. Disconnect the air fuel ratio sensor connector.

   2. Remove the No. 1 integration relay from the No. 1 engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition F62-2 (+B) - 1F-4 Always Below 1 Ω F86-2 (+B) - 1F-4 Always Below 1 Ω F62-2 (+B) or 1F-4 - Body ground Always 10 kΩ or higher F86-2 (+B) or 1F-4 - Body ground Always 10 kΩ or higher

   4. Reinstall the No. 1 integration relay.

   5. Reconnect the air fuel ratio sensor connector.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY)

   OK

6. CHECK TERMINAL VOLTAGE (NO. 1 INTEGRATION RELAY)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to No. 1 Integration Relay)

      Remove the No. 1 integration relay from the No. 1 engine room relay block and junction block assembly.

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

      Standard Voltage
      Tester Connection Condition Specified Condition 1D-1 - Body ground Always 11 to 14 V

   3. Reinstall the No. 1 integration relay.

   
   

   OK

   REPLACE NO. 1 INTEGRATION RELAY

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - NO. 1 INTEGRATION RELAY)