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 drivability.

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 / Data List / 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 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.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.

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 TEMPERATURE)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the tester ON.
Enter the following menus: Powertrain / Engine / Data List / Intake Air.

Read the value displayed on the tester.

Standard
Same as actual intake air temperature.

Result

Temperature Displayed	Proceed to
-40°C (-40°F)	A
140°C (284°F)	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).

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)
1. Disconnect the mass air flow meter connector.
2. Connect terminals THA and E2 of the mass air flow meter wire harness side connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the engine switch on (IG).
5. Turn the tester ON.
6. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
7. Read the value displayed on the tester.
  
  Standard
  
  140°C (284°F)
8. Reconnect the mass air flow meter connector.
NG
READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM) Click here

OK

REPLACE MASS AIR FLOW METER Click here
READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM)
1. Disconnect the mass air flow meter connector.
2. Connect terminals THA and E2 of the ECM connector.
  
  Tech Tips
  
  Before checking, do visual and contact pressure checks on the ECM connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the engine switch on (IG).
5. Turn the tester ON.
6. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
7. Read the value displayed on the tester.
  
  Standard
  
  140°C (284°F)
8. Reconnect the mass air flow meter connector.
NG
REPLACE ECM Click here

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)
1. Disconnect the mass air flow meter connector.
2. Connect the intelligent tester to the DLC3.
3. Turn the engine switch on (IG).
4. Turn the tester ON.
5. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
6. Read the value displayed on the tester.
  
  Standard
  
  -40°C (-40°F)
7. Reconnect the mass air flow meter connector.
NG
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM) Click here

OK

REPLACE MASS AIR FLOW METER Click here
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM)
1. Disconnect the mass air flow meter connector.
2. Disconnect the ECM connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the engine switch on (IG).
5. Turn the tester ON.
6. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
7. Read the value displayed on the tester.
  
  Standard
  
  -40°C (-40°F)
8. Reconnect the mass air flow meter connector.
NG
REPLACE ECM Click here

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR

SFI SYSTEM, Diagnostic DTC:P0112, P0113