Audi Workshop Service and Repair Manuals

The altitude sender is located in the Diesel direct injection system control unit. The intake manifold pressure sender is a separate component and is located together with the intake manifold temperature sender in a housing on intake manifold.

Special tools and workshop equipment required

• ◆ Turbocharger tester V.A.G 1397 A

Note:

The turbocharger test unit is required to provide an independent figure for comparison. The turbocharger test unit must be set to measuring range I (absolute pressure). A barometer can be used instead.

Test sequence

• ‒ Read data block, Display group 010, engine not running
  => Page 01-104.

→ Display on VAS 5051:

• ‒ Observe the readouts in display zone -2- (altitude sender -F96) and display zone -3- (intake manifold pressure sender -G71).
• ‒ Specification: The pressures should be the same.
  Tolerance: ± 30 mbar

If value in display zone 2 deviates:

• ‒ Fit a new engine control unit => Page 23-40.

Value in display zone 3 deviates:

• ‒ Start engine and run at idling speed.
• ‒ → Unplug connector at intake manifold pressure sender -G71 -arrow-.

• ‒ Read measured value block, Display Group 010, engine running at idling speed => Page 01-104.

→ Display on VAS 5051:

• ‒ Observe figures in display zone -3- (intake manifold pressure sender -G71).
• ‒ Specification: displayed reading should decrease continuously until it equals value of altitude sender (display zone 2)
• ‒ Press the ◂ button to exit from the function "08 - Read data block".
• ‒ Select diagnosis function "06 - End output".

If the specification is obtained:

• ‒ Renew intake manifold pressure sender with intake manifold temperature sender.

If the specification is not obtained:

Checking wiring connections

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
  => Page 23-37.
• ‒ → Test for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short circuit as necessary.

If no fault is found:

• ‒ Fit a new engine control unit => Page 23-40.