124 Intake Air Temperature Sensor - Below Limit

P0112

124 Intake Air Temperature Sensor - Below Limit

Function
The intake air temperature sensor consists of a temperature-dependent resistance element, which is integrated in the mass air flow sensor. The resistance element of the sensor has a negative temperature coefficient (NTC) and is part of a voltage divider circuit which receives a supply voltage of 5 V. The voltage, which drops due to the resistance element, is input into the DME control module by means of the analog-to-digital converter, and provides a measurement for the temperature. In the DME control module, a table is stored which states the appropriate temperature for each voltage value and therefore compensates the non-linear relationship between voltage and temperature.

Diagnosis conditions

P0112
Time elapsed after engine start-up > 5 minutes

P0113
Time elapsed after engine start-up > 2 sec.

NOTE: A substitute value (approx. 20 °C) is used in the event of a fault.

P0112 - P0113:

Wiring Diagram







Diagnosis Procedure










1 Check temperature sensor in MAF sensor.
1. Remove connector of MAF sensor.
2. Connect ohmmeter to MAF sensor, pins 1 and 3.

Display: 2.3 - 2.7 k ohms at 20 °C

2 Check wiring from DME control module to temperature sensor for continuity.
1. Remove connector of MAF sensor.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Connect ohmmeter to special tool 9637, pin III/34, and MAF sensor connector, pin 1.

Display: 0 - 5 ohms.

If infinity ohms is displayed, check wiring harness for chafing and pinching damage.

3 Check wiring from DME control module to temperature sensor for short to ground.
1. Remove connector of MAF sensor.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Connect ohmmeter to special tool 9637, pin III/34, and ground.

Display: infinity ohms

If 0 - 5 ohms is displayed, check wiring harness for chafing and pinching damage.

4 Check wiring from DME control module to temperature sensor for short to B+.
1. Remove connector of MAF sensor.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Switch on the ignition.
4. Connect voltmeter to special tool 9637, pin III/34 (positive), and ground.

Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.