SFI SYSTEM, Diagnostic DTC: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 P0112 or P0113 is 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)

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)

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 / Intake Air.

Temperature Displayed	Malfunction
-40°C (-40°F)	Open circuit
140°C (284°F)	Short circuit

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. 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 INTELLIGENT TESTER (INTAKE AIR)

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 / 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)	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).

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

CHECK FOR INTERMITTENT PROBLEMS Click here

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

Text in Illustration
*1	Mass Air Flow Meter
*2	ECM
*3	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 / Intake Air.
Read the value displayed on the tester.

Standard value

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

Standard value
140°C (284°F)

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

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 (Check for Open)

Tester Connection	Condition	Specified Condition
B53-1 (THA) - B8-87 (THA)	Always	Below 1 Ω
B53-2 (E2) - B8-88 (ETHA)	Always	Below 1 Ω

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM Click here

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 / Intake Air.
6. Read the value displayed on the tester.
  
  Standard value
  
  -40°C (-40°F)
7. Reconnect the mass air flow meter connector.
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 (Check for Short)

Tester Connection	Condition	Specified Condition
B53-1 (THA) or B8-87 (THA) - Body ground	Always	10 kΩ or higher

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM Click here