ECD SYSTEM (w/o EGR Cooler), Diagnostic DTC:P0110, P0112, P0113

DTC Code	DTC Name
P0110	Intake Air Temperature Circuit
P0112	Intake Air Temperature Circuit Low Input
P0113	Intake Air Temperature Circuit High Input

DESCRIPTION

The Intake Air Temperature (IAT) sensor, built into the Mass Air Flow (MAF) meter, monitors the IAT. The IAT senor has a thermistor that varies its resistance depending on the temperature of the intake air. When the air temperature is low, the resistance in the thermistor increases. When the air temperature is high, the resistance decreases. The variations in resistance are communicated to the ECM as change in voltage (see Fig. 1). The IAT sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the IAT sensor from terminal THA via resister R.

The resister R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes in accordance with changes in the IAT, the voltage at terminal THA also changes. Based on this signal, the ECM increases the fuel injection volume to improve the driveability during cold engine operation.

The Intake Air Temperature (IAT) sensor, mounted on the air cleaner hose, monitors the IAT.

The IAT sensor has a thermistor that varies its resistance depending on the temperature of the intake air. When the air temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance decreases. The variations in resistance are communicated to the ECM as changes in voltage (see Fig. 1).

The IAT sensor is connected to the ECM (see below). The 5 V power source voltage in the ECM is applied to the IAT sensor from terminal THA via resistor R.

The resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes in accordance with changes in the IAT, the voltage at terminal THA also changes. Based on this signal, the ECM increases the fuel injection volume to improve the driveability during cold engine operation.

DTC No.	DTC Detection Condition	Trouble Area
P0110	Open or short in IAT sensor circuit for 0.5 seconds (1 trip detection logic)	Open or short in IAT sensor circuit IAT sensor (built into MAF meter) ECM
P0112	Short in IAT sensor circuit for 0.5 seconds (1 trip detection logic)	Open or short in IAT sensor circuit IAT sensor (built into MAF meter) ECM
P0113	Open in IAT sensor circuit for 0.5 seconds (1 trip detection logic)	Open or short in IAT sensor circuit IAT sensor (built into MAF meter) ECM

Tech Tips

When DTC P0110, P0112 or P0113 is detected, check the intake air temperature by entering the following menus on the intelligent tester: Powertrain / Engine / Data List / Intake Air.

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

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

If DTCs related 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 conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

Note

After replacing the ECM, the new ECM needs registration Click here and initialization Click here.

PROCEDURE

READ VALUE USING INTELLIGENT TESTER (INTAKE AIR TEMPERATURE)

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

Read the values.

OK
Same value as the actual air temperature.

Result

Temperature Displayed	Proceed to
-40°C (-40°F)	A
140°C (284°F) or more	B
OK (same as air temperature near intake manifold)	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 more.

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)
1. Disconnect the A4 MAF meter connector.
2. Connect terminals 4 and 5 of the MAF meter wire harness side connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the ignition switch ON and turn the intelligent tester ON.
5. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
6. Read the values.
  
  OK
  
  140°C (284°F) or more
OK
CONFIRM GOOD CONNECTION AT SENSOR. IF OK, REPLACE MAF METER

NG
READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM)
1. Disconnect the A4 MAF meter connector.
2. Connect terminals THA and E2 of the E8 ECM connector.
  
  Tech Tips
  
  Before checking, perform a visual and contact pressure check on the ECM connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the ignition switch ON and turn the intelligent tester ON.
5. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
6. Read the values.
  
  OK
  
  140°C (284°F) or more
OK
REPAIR OR REPLACE HARNESS AND CONNECTOR

NG

CONFIRM GOOD CONNECTION AT ECM. IF OK, REPLACE ECM
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)
1. Disconnect the A4 MAF meter.
2. Connect the intelligent tester to the DLC3.
3. Turn the ignition switch ON and turn the intelligent tester ON.
4. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
5. Read the values.
  
  OK
  
  -40°C (-40°F)
OK
REPLACE MASS AIR FLOW METER Click here

NG
READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM)
1. Disconnect the A4 MAF meter.
2. Disconnect the E8 ECM connector.
3. Connect the intelligent tester to the DLC3.
4. Turn the ignition switch ON and turn the intelligent tester ON.
5. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
6. Read the values.
  
  OK
  
  -40°C (-40°F)
OK
REPAIR OR REPLACE HARNESS AND CONNECTOR

NG

REPLACE ECM Click here