Intake Air Temperature (IAT) sensor -G42-, checking

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Special Tools - Intake Air Temperature (IAT) Sensor -G42-, Checking

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Special tools and equipment

VAG1526 A
VAG1594 A
VAG1598/31
VAS5051 with VAS5051/1

NOTE: The Intake Air Temperature (IAT) sensor -G42- is integrated in the Mass Air Flow (MAF) sensor -G70-.

Test sequence

Connect testing and information system VAS5051. Refer to Vehicle diagnostic, testing and information system VAS5051, connecting and select functions and select vehicle system "01 - Engine electronics" in selection. Engine must be running at idling speed.

Fig 2: Diagnostic System VAS 5051: Display

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Display on VAS5051:

Under -1- select diagnostic function "08 - Read measured value block".

Fig 3: Diagnostic System VAS 5051: Display

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Display on VAS5051:

1 - Enter display group

Enter "004" for "display group number 004" in zone -2- and confirm entry by pressing -Q- button.

Fig 4: Diagnostic System VAS 5051: Display

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Display on VAS5051:

Check indication in display field -4-.

	Display zones
	1	2	3	4
Display group 004: Intake air temperature with engine idling
Display	xxxx RPM	xx.x V	xxx.x°C	xxx.x°C
Display	Engine speed	Battery voltage	Coolant temperature	Intake air temperature
Range				-48.0 to 143.0°C
Specif. value	xxxx RPM	12.0 to 15.0 V	80.0 to 110.0°C	Between ambient temperature and up to 110°C 1)

1) If a temperature is displayed which deviates greatly from the ambient temperature of the sensor, check sensor and sensor wiring for terminal resistances and open circuit.

Exit function "08 - Read measured value block" by pressing ← button.

Checking wiring

Fig 5: Disconnecting Connector To Mass Air Flow (MAF) Sensor

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Disconnect connector (arrow) to mass air flow sensor.
Connect test box VAG1598/31 to wiring harness for engine control module; do not connect engine control module. Refer to Wiring and component check with test box VAG 1598/31 .

Fig 6: Identifying 5-Pin Electrical Harness Connector & Terminals

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Check for open circuit and short to positive or ground in following wiring connection:

Connector Terminal	Test box VAG1598/31 Socket
5	26

Repair any open/short circuit as necessary.
Check all wires for short to one another.

If no wiring malfunction is detected:

Replace Mass Air Flow (MAF) sensor -G70-.