SFI SYSTEM (w/o EGR System), Diagnostic DTC:P0112, P0113
| DTC Code | DTC Name |
|---|---|
| P0112 | Intake Air Temperature Circuit Low Input |
| P0113 | Intake Air Temperature Circuit High Input |
DESCRIPTION
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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).
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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.
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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.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0112 | Short in intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic) |
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| P0113 | Open in intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic) |
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Tech Tips
When any of these DTCs are set, check the intake air temperature by entering the following menus on the intelligent tester: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
| Temperature Displayed | Malfunction |
|---|---|
| -40°C (-40°F) | Open circuit |
| 140°C (284°F) | Short circuit |
WIRING DIAGRAM
INSPECTION PROCEDURE
Tech Tips
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
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READ VALUE USING INTELLIGENT TESTER (INTAKE AIR)
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Connect the intelligent tester to the DLC3.
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Turn the power switch on (IG).
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Turn the tester on.
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Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
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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
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If there is an open circuit, the tester indicates -40°C (-40°F).
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If there is a short circuit, the tester indicates 140°C (284°F).
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B 
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS) Click here
C 
CHECK FOR INTERMITTENT PROBLEMS Click here
A 
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READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN WIRE HARNESS)
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Confirm good connection at the mass air flow meter sub-assembly.
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Disconnect the mass air flow meter sub-assembly connector.
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Connect terminals THA and E2 of the mass air flow meter sub-assembly connector on the wire harness side.
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Connect the intelligent tester to the DLC3.
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Turn the power switch on (IG).
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Turn the tester on.
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Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
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Read the value displayed on the tester.
Standard 140°C (284°F) 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)
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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
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CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)
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Disconnect the mass air flow meter sub-assembly connector.
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Disconnect the ECM connector.
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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 -
Reconnect the mass air flow meter sub-assembly connector.
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Reconnect the ECM connector.
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)
OK
REPLACE ECM Click here
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READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)
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Text in Illustration *1 Mass Air Flow Meter Sub-assembly *2 ECM Disconnect the mass air flow meter sub-assembly connector.
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Connect the intelligent tester to the DLC3.
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Turn the power switch on (IG).
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Turn the tester on.
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Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
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Read the value displayed on the tester.
Standard -40°C (-40°F) -
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
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CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)
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Disconnect the mass air flow meter sub-assembly connector.
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Disconnect the ECM connector.
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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 -
Reconnect the mass air flow meter sub-assembly connector.
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Reconnect the ECM connector.
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)
OK
REPLACE ECM Click here
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