audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

Checking engine speed sender -G28 > < Checking power supply relay for Motronic system -J271
Motronic injection and ignition system (4-cyl. turbo)
Checking ignition system
Checking intake air temperature sender -G42
 
G24-0021

Special tools and workshop equipment required

  • ◆ V.A.G 1526 A
  • ◆ V.A.G 1594 A
  • ◆ V.A.G 1598/31
  • ◆ VAS 5051 with VAS 5051/1

Fitting location => Fitting locations overview, Page 24-5

Test sequence

  • ‒ Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in the selection. For this purpose, the engine must be running at idling speed.
 
A01-0122

→ Display on VAS 5051:

  • ‒ Under -1- select the diagnostic function "08 - Read measured value block".
 
A01-0130

→ Display on VAS 5051:

  •     1 -    Enter display group
    max. input value = 255
  • ‒ Enter "004" for "display group number 004" in zone -2- and confirm the entry by pressing the Q key.

 
A01-0139

→ Display on VAS 5051:

  • ‒ Check intake air temperature sender in display zone -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...143.0 °C

Specified value

xxxx rpm

12.0...15.0 V

80.0...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 sender, check sender and sender wiring for contact resistances and open circuit.

  • ‒ Exit the function "08 - Read measured value block" by pressing the ◂key.

Checking wiring

 
A28-0047
  • ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page 24-19.
  • ‒ → Unplug connector -1- at coolant temperature sender -G42-2-.

 
N24-0231
  • ‒ → Check for open circuit and short to positive or earth in the following wiring connections:

Connector
Contact

Test box V.A.G 1598/31
Socket

1

85

2

108

  • ‒ Test for short circuits between the two wires.
  • ‒ Rectify any open/short circuit as necessary.

If no wiring fault is detected:

  • ‒ Check the intake air temperature sender.

Checking sender:

 
A24-0040
  • ‒ → Connect multimeter to sender to measure resistance.

Specifications:

Temperature °C

Resistance kω

-20

approx. 13.8

0

approx. 5.5

20

approx. 2.4

40

approx. 1.1

60

approx. 0.6

If specified value is not attained:

  • ‒ Replace intake air temperature sender.

Checking engine speed sender -G28 > < Checking power supply relay for Motronic system -J271