P0112, P0113

DTC Code	DTC Name
P0112	Intake Air Temperature Circuit Low Input
P0113	Intake Air Temperature Circuit High Input

DESCRIPTION

The intake air temperature sensor, mounted on 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 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).
The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
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. The ECM continues operating in fail-safe mode until a pass condition is detected.

DTC No.	DTC Detection Condition	Trouble Area
P0112	Short in the intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic).	Short in intake air temperature sensor circuit Intake air temperature sensor (built into mass air flow meter) ECM
P0113	Open in the intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic).	Open in intake air temperature sensor circuit Intake air temperature sensor (built into mass air flow meter) ECM

Tech Tips

When either of these DTCs is stored, check the intake air temperature by entering the following menus: Powertrain / Engine and ECT / All Data / Intake Air.

Temperature Displayed	Malfunction
-40°C (-40°F)	Open circuit
140°C (284°F) or higher	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 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 0.18 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

Frequency of Operation

Continuous

CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the intelligent tester on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the intelligent tester on.
Wait 5 seconds or more.
Enter the following menus: Powertrain / Engine and ECT / DTC.
Read the 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.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0112, P0113.

Check the DTC judgment result.

Intelligent tester Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment 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 check the DTC judgment result again.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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

READ VALUE USING INTELLIGENT TESTER (INTAKE AIR)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the intelligent tester on.
Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.

Read the value displayed on the intelligent 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

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

Disconnect the mass air flow meter connector.
Connect terminals 4 (THA) and 5 (E2) of the mass air flow meter wire harness side connector.
Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the intelligent tester on.
Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.

Read the value displayed on the intelligent tester.

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

Text in Illustration
*1	Mass Air Flow Meter
*2	ECM
*a	Front view of wire harness connector (to Mass Air Flow Meter)

NG

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

OK

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

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

Disconnect the mass air flow meter connector.
Disconnect the ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A3-4 (THA) - D3-29 (THA)	Always	Below 1 Ω
A3-5 (E2) - D1-28 (E2)	Always	Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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

READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)
Text in Illustration

*1 Mass Air Flow Meter

*2 ECM
1. 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 intelligent tester on.
5. Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.
6. Read the value displayed on the intelligent tester.
  
  Standard value
  
  -40°C (-40°F)
NG
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) Click here

OK

REPLACE MASS AIR FLOW METER Click here

Standard value
-40°C (-40°F)

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

Disconnect the mass air flow meter connector.
Disconnect the ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A3-4 (THA) or D3-29 (THA) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

REPLACE ECM Click here

SFI SYSTEM, Diagnostic DTC:P0112, P0113