SFI SYSTEM (w/ EGR System), Diagnostic DTC:P0112, P0113

DESCRIPTION

• The intake air temperature sensor, in the mass air flow meter sub-assembly, 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, the voltage at terminal THA varies accordingly. 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 set, 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.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER (INTAKE AIR)

   
   

   1. Connect the intelligent tester to the DLC3.

   2. Turn the power switch on (IG).

   3. Turn the tester on.

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

   5. Read the value displayed on the tester.

      Standard
      Same as actual intake air temperature.

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

      Tech Tips

      
      

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

      
      

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

   
   

   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. Confirm good connection at the mass air flow meter sub-assembly.

      

      Text in Illustration

      *1	Mass Air Flow Meter Sub-assembly	*2	ECM
      *3	Front view of wire harness connector (to Mass Air Flow Meter Sub-assembly)	-	-

   2. Disconnect the mass air flow meter sub-assembly connector.

   3. Connect terminals THA and E2 of the mass air flow meter sub-assembly connector on the wire harness side.

   4. Connect the intelligent tester to the DLC3.

   5. Turn the power switch on (IG).

   6. Turn the tester on.

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

   8. Read the value displayed on the tester.

      Standard
      140°C (284°F)

   9. Reconnect the mass air flow meter sub-assembly connector.

   
   

   NG

   CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM) Click here

   OK

   REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Click here

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

   
   

   1. Disconnect the mass air flow meter sub-assembly connector.

      

   2. Disconnect the ECM connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition D3-1 (THA) - D1-96 (THA) Always Below 1 Ω D3-2 (E2) - D1-128 (ETHA) Always Below 1 Ω

      Text in Illustration

      *1

      Front view of wire harness connector (to Mass Air Flow Meter Sub-assembly)

      *2

      Front view of wire harness connector (to ECM)

   4. Reconnect the mass air flow meter sub-assembly connector.

   5. Reconnect the ECM connector.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

   OK

   REPLACE ECM Click here

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

   
   
   1. 

      Text in Illustration

      *1	Mass Air Flow Meter Sub-assembly
      *2	ECM

      Disconnect the mass air flow meter sub-assembly connector.

   2. Connect the intelligent tester to the DLC3.

   3. Turn the power switch on (IG).

   4. Turn the tester on.

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

   6. Read the value displayed on the tester.

      Standard
      -40°C (-40°F)

   7. Reconnect the mass air flow meter sub-assembly connector.

   
   

   NG

   CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM) Click here

   OK

   REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Click here

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

   
   

   1. Disconnect the mass air flow meter sub-assembly connector.

      

   2. Disconnect the ECM connector.

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

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition D3-1 (THA) or D1-96 (THA) - Body ground Always 10 kΩ or higher

      Text in Illustration

      *1

      Front view of wire harness connector (to Mass Air Flow Meter Sub-assembly)

      *2

      Front view of wire harness connector (to ECM)

   4. Reconnect the mass air flow meter sub-assembly connector.

   5. Reconnect the ECM connector.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

   OK

   REPLACE ECM Click here