Code No. P0113: Intake Air Temperature Sensor Circuit High Input

OPERATION

A power voltage of 5 V is applied to the intake air temperature sensor power terminal of air flow sensor connector from the engine-ECU connector terminal ATS.
The power voltage is earthed to the engine-ECU connector terminal AFSE from the intake air temperature sensor connector terminal.

FUNCTION

The intake air temperature sensor converts the intake air temperature into a voltage and inputs the voltage signal to the engine-ECU.
In response to the signal, the engine-ECU corrects the fuel injection amount, etc.
The intake air temperature sensor is a kind of resistor, which has characteristics to reduce its resistance as the intake air temperature rises. Therefore, the sensor output voltage varies with the intake air temperature, and becomes lower as the intake air temperature rises.

TROUBLE JUDGEMENT

Check Condition

More than 2 seconds have passed since the engine starting sequence was completed.

Judgement Criterion

Intake air temperature sensor output voltage is more than 4.6 V (corresponding to an intake air temperature of -40°C or less) for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

Control as if the intake air temperature is 25°C.

PROBABLE CAUSES

Failed intake air temperature sensor
Open circuit or harness damage in intake air temperature sensor circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Item 5: Intake air temperature sensor

OK: At ambient temperature (atmospheric temperature) or equivalent.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Go to Step 2.

STEP 2. Check intake air temperature sensor itself.

Air flow sensor connector check.
Intake air temperature sensor check (Refer to ).

Q. Is the check result normal?

	Go to Step 3.

	Repair or replace the connector, or replace the air flow sensor.

STEP 3. Perform voltage measurement at air flow sensor connector.

Disconnect connector, and measure at harness side.
Ignition switch: "ON"
Voltage between terminal engine-ECU ATS line and body earth.

OK: 4.5 - 4.9 V

Q. Is the check result normal?

	Go to Step 6.

	Go to Step 4.

STEP 4. Check of open circuit in ATS line between air flow sensor connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.

STEP 5. M.U.T.-III data list

Item 5: Intake air temperature sensor

OK: At ambient temperature (atmospheric temperature) or equivalent.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Replace the engine-ECU.

STEP 6. Perform resistance measurement at air flow sensor connector.

Disconnect connector, and measure at harness side.
Resistance between terminal engine-ECU AFSE line and body earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 8.

	Go to Step 7.

STEP 7. Check of open circuit, and damage in AFSE line between air flow sensor connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.

STEP 8. Check of damage in ATS line between air flow sensor connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.