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, mounted on 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 is low, the resistance of the thermistor increases. When the temperature is 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.
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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, 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 DTC P0112 or P0113 is 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.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0112 | A short in the intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic). |
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| P0113 | An open in the intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic). |
|
Tech Tips
When any of these DTCs are output, check the intake air temperature using the GTS. Enter the following menus: 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 |
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 circuit and stores a DTC.
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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 less than 0.18 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and stores DTC P0112.
MONITOR STRATEGY
| Frequency of Operation | Continuous |
CONFIRMATION DRIVING PATTERN
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Connect the GTS to the DLC3.
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Turn the power switch on (IG) and turn the GTS on.
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Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
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Turn the power switch off and wait for at least 30 seconds.
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Turn the power switch on (IG) and turn the GTS on.
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Wait 0.5 seconds or more.
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Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
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Read the pending DTCs.
Tech Tips
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If a pending DTC is output, the system is malfunctioning.
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If a pending DTC is not output, perform the following procedure.
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Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
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Input the DTC: P0112 or P0113.
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Check the DTC judgment result.
GTS Display Description NORMAL
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DTC judgment completed
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System normal
ABNORMAL
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DTC judgment completed
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System abnormal
INCOMPLETE
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DTC judgment not completed
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Perform driving pattern after confirming DTC enabling conditions
N/A
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Unable to perform DTC judgment
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Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
Tech Tips
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If the judgment result shows NORMAL, the system is normal.
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If the judgment result shows ABNORMAL, the system has a malfunction.
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If the judgment result shows INCOMPLETE or N/A, perform the Confirmation Driving Pattern and check the DTC judgment result again.
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WIRING DIAGRAM
INSPECTION PROCEDURE
Tech Tips
Read freeze frame data using the GTS. 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 GTS (INTAKE AIR)
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Connect the GTS to the DLC3.
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Turn the power switch on (IG).
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Turn the GTS 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 GTS.
OK Same as actual intake air temperature. Result Result Proceed to -40°C (-40°F) A 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 GTS indicates -40°C (-40°F).
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If there is a short circuit, the GTS indicates 140°C (284°F).
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B 
READ VALUE USING GTS (CHECK FOR SHORT IN WIRE HARNESS) Click here
C 
CHECK FOR INTERMITTENT PROBLEMS Click here
A 
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READ VALUE USING GTS (CHECK FOR OPEN IN WIRE HARNESS)
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Disconnect the mass air flow meter sub-assembly connector.
Text in Illustration *1 Mass Air Flow Meter Sub-assembly *2 ECM *a Front view of wire harness connector
(to Mass Air Flow Meter Sub-assembly)
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Connect terminals 1 (THA) and 2 (E2) of the mass air flow meter sub-assembly connector on the wire harness side.
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Connect the GTS to the DLC3.
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Turn the power switch on (IG).
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Turn the GTS 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 GTS.
Standard Value 140°C (284°F) Tech Tips
Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly Click here.
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 Tester Connection Condition Specified Condition F39-1 (THA) - F70-93 (THA) Always Below 1 Ω F39-2 (E2) - F70-94 (ETHA) Always Below 1 Ω
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE ECM Click here
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READ VALUE USING GTS (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 GTS to the DLC3.
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Turn the power switch on (IG).
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Turn the GTS 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 GTS.
Standard Value -40°C (-40°F) Tech Tips
Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly Click here.
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 Tester Connection Condition Specified Condition F39-1 (THA) or F70-93 (THA) - Body ground Always 10 kΩ or higher
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE ECM Click here
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