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, 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, 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)	Short in intake air temperature sensor circuit Intake air temperature sensor (built into mass air flow meter) ECM
P0113	Open in 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

DTC No.

DTC Detection Condition

Trouble Area

P0112

Short in 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 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 any of these DTCs are set, check the intake air temperature by entering the following menus on the GTS: Powertrain / Engine and ECT / Data List / Intake Air.

Temperature Displayed	Malfunction
-40°C (-40°F)	Open circuit
Higher than 128°C (262°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 and sets a DTC.

Example:

If the sensor output voltage is more 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 sets 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 sets DTC P0112.

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

MONITOR STRATEGY

Frequency of Operation

Continuous

CONFIRMATION DRIVING PATTERN

Connect the GTS to the DLC3.
Turn the power switch on (IG) and turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG) and turn the GTS on.
Wait 0.5 seconds or more.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
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.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0112 or P0113.

Check the DTC judgment result.

GTS 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's 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.

WIRING DIAGRAM


*a	Mass Air Flow Meter

CAUTION / NOTICE / HINT

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

READ VALUE USING GTS (INTAKE AIR)

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

Read the value displayed on the GTS.

Standard
Same as actual intake air temperature.

Result

Result	Proceed to
Displayed temperature is -40°C (-40°F)	A
Displayed temperature is higher than 128°C (262°F)	B
Same as actual intake air temperature	C

Tech Tips

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

If there is a short circuit, the GTS indicates higher than 128°C (262°F).

B

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

C

CHECK FOR INTERMITTENT PROBLEMS Click here

A

READ VALUE USING GTS (CHECK FOR OPEN IN WIRE HARNESS)

Confirm good connection at the mass air flow meter.

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.
Connect terminals THA and E2 of the mass air flow meter connector on the wire harness side.
Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.
Read the value displayed on the GTS.

Standard

Higher than 128°C (262°F)
Reconnect the mass air flow meter connector.

Standard
Higher than 128°C (262°F)

OK

REPLACE MASS AIR FLOW METER Click here

NG

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
F39-1 (THA) - F5-96 (THA)	Always	Below 1 Ω
F39-2 (E2) - F5-129 (ETHA)	Always	Below 1 Ω

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

OK

REPLACE ECM Click here

NG

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

READ VALUE USING GTS (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 GTS to the DLC3.
3. Turn the power switch on (IG).
4. Turn the GTS on.
5. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.
6. Read the value displayed on the GTS.
  
  Standard
  
  -40°C (-40°F)
7. Reconnect the mass air flow meter connector.
OK
REPLACE MASS AIR FLOW METER Click here

NG

Text in Illustration
*1	Mass Air Flow Meter
*2	ECM

Standard
-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
F39-1 (THA) or F5-96 (THA) - Body ground	Always	10 kΩ or higher

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

OK

REPLACE ECM Click here

NG

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

SFI SYSTEM, Diagnostic DTC:P0112, P0113