SFI SYSTEM, Diagnostic DTC:P0112, P0113

DESCRIPTION

• The intake air temperature sensor, mounted in the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature becomes low, the resistance of the thermistor increases. When the temperature becomes high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see Fig. 1).

• The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R which is located inside the ECM.

• Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.

  Tech Tips

  When any of DTCs P0112 and P0113 are stored, the ECM enters fail-safe mode. During fail-safe mode, the intake air temperature is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

MONITOR DESCRIPTION

The ECM monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the intake air temperature sensor and stores a DTC.

Example:

If the sensor output voltage is higher than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the intake air temperature sensor circuit and stores DTC P0113. Conversely, if the output voltage is below 0.14 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit and stores DTC P0112.

If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.

MONITOR STRATEGY

CONFIRMATION DRIVING PATTERN

1. Connect the intelligent tester to the DLC3.

2. Turn the ignition switch to ON and turn the tester on.

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

4. Turn the ignition switch off and wait for at least 30 seconds.

5. Turn the ignition switch to ON and turn the tester on.

6. Wait 5 seconds or more.

7. Enter the following menus: Powertrain / Engine and ECT / DTC.

8. Read pending DTCs.

   Tech Tips

   
   

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

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

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

10. Input the DTC: P0112 or P0113.

11. Check the DTC judgment result.

    Tester 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

    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 the Confirmation Driving Pattern and the DTC judgment result again.

WIRING DIAGRAM

for LHD

*a	Intake Air Temperature Sensor (Mass Air Flow Meter)

for RHD

*a	Intake Air Temperature Sensor (Mass Air Flow Meter)

CAUTION / NOTICE / HINT

PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER (INTAKE AIR TEMPERATURE)

   
   

   1. Connect the intelligent tester to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the tester on.

   4. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

   5. Read the value displayed on the tester.

      OK
      Same as actual intake air temperature.

      Result

      Result	Proceed to
      -40°C (-40°F)	A
      140°C (284°F) or higher	B
      Same as actual intake air temperature	C

      Tech Tips

      
      

      • If there is an open circuit, the intelligent tester indicates -40°C (-40°F).

      
      

      • If there is a short circuit, the intelligent tester indicates 140°C (284°F) or higher.

   
   

   B

   READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS) Click here

   C

   CHECK FOR INTERMITTENT PROBLEMS Click here

   A

2. READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN WIRE HARNESS)

   
   
   1. 

      Text in Illustration

      *1	Mass air flow meter
      *2	ECM
      *a	Front view of wire harness connector (to Mass air flow meter)

      Disconnect the mass air flow meter connector.

   2. Connect terminals 1 (THA) and 2 (E2) of the mass air flow meter wire harness side connector.

   3. Connect the intelligent tester to the DLC3.

   4. Turn the ignition switch to ON.

   5. Turn the tester on.

   6. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

   7. Read the value displayed on the tester.

      Standard value
      140°C (284°F) or higher

      Tech Tips

      Perform "Inspection After Repairs" after replacing the mass air flow meter Click here.

   
   

   OK

   CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE MASS AIR FLOW METER Click here

   NG

3. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

   
   

   1. Disconnect the mass air flow meter 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 B73-1 (THA) - B22-90 (THA) Always Below 1 Ω B73-2 (E2) - B22-122 (ETHA) Always Below 1 Ω
      for RHD Tester Connection Condition Specified Condition B73-1 (THA) - B23-90 (THA) Always Below 1 Ω B73-2 (E2) - B23-122 (ETHA) Always Below 1 Ω

   
   

   OK

   CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

4. READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)

   
   
   1. 

      Text in Illustration

      *1	Mass air flow meter
      *2	ECM

      Disconnect the mass air flow meter connector.

   2. Connect the intelligent tester to the DLC3.

   3. Turn the ignition switch to ON.

   4. Turn the tester on.

   5. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

   6. Read the value displayed on the tester.

      Standard value
      -40°C (-40°F)

      Tech Tips

      Perform "Inspection After Repairs" after replacing the mass air flow meter Click here.

   
   

   OK

   REPLACE MASS AIR FLOW METER Click here

   NG

5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

   
   

   1. Disconnect the mass air flow meter 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 B73-1 (THA) or B22-90 (THA) - Body ground Always 10 kΩ or higher
      for RHD Tester Connection Condition Specified Condition B73-1 (THA) or B23-90 (THA) - Body ground Always 10 kΩ or higher

   
   

   OK

   REPLACE ECM Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR