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 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, 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 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: Powertrain / Engine and ECT / Data List / 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.

CONFIRMATION DRIVING PATTERN

Turn the ignition switch to ON and wait for 5 seconds or more.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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 TEMPERATURE)

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

Read the value displayed on the 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)

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 1 (THA) and 2 (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 tester on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
Read the value displayed on the tester.

Standard value

140°C (284°F) or higher
Reconnect the mass air flow meter connector.

Tech Tips

Perform "Inspection After Repairs" after replacing the mass air flow meter Click here.

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

OK

CONFIRM GOOD CONNECTION TO SENSOR. IF 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

for RHD
Tester Connection	Condition	Specified Condition
B73-1 (THA) - B23-90 (THA)	Always	Below 1 Ω
B73-2 (E2) - B23-122 (ETHA)	Always	Below 1 Ω

for LHD
Tester Connection	Condition	Specified Condition
B73-1 (THA) - B22-90 (THA)	Always	Below 1 Ω
B73-2 (E2) - B22-122 (ETHA)	Always	Below 1 Ω

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

OK

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

NG

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

READ VALUE USING INTELLIGENT TESTER (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 intelligent tester to the DLC3.
3. Turn the ignition switch to ON.
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 value
  
  -40°C (-40°F)
7. Reconnect the mass air flow meter connector.
  
  Tech Tips
  
  Perform "Inspection After Repairs" after replacing the mass air flow meter Click here.
OK
REPLACE MASS AIR FLOW METER Click here

NG

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

for RHD
Tester Connection	Condition	Specified Condition
B73-1 (THA) or B23-90 (THA) - Body ground	Always	10 kΩ or higher

for LHD
Tester Connection	Condition	Specified Condition
B73-1 (THA) or B22-90 (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