check engine AUDI A4 1999 B5 / 1.G AWM Engine Charge Pressure Leak Test Workshop Manual

21-24

Mechanical air recirculation valve,
checking


Note:

The mechanical air recirculation valve is
upstream of the exhaust turbocharger. It is
opened via vacuum by the recirculating valve
for turbocharger -N249- under conditions of
overrun, idling and partial load. This reduces
the charge pressure upstream of the throttle
valve. A high turbocharger speed is thus
maintained.
Check the air recirculation valve if the engine is
not producing full power, or jerking when the
throttle is opened and closed.

Special tools and equipment

Hand vacuum pump VAG 1390
Pa
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ge pressure leak test with VAG 1687
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21-30

Checking power supply

Note:
The power supply for the recirculating valve is via
the fuel pump relay.

Test requirements:

Fuse for recirculating valve OK.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Fuel pump relay OK.

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24


- Disconnect wiring connector from valve.

- Connect voltage tester VAG 1527 B as follows:Connector
Measure to
Pa
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21-32
If the LED lamp does not flash or if it lights up
continuously:

- Connect VAG 1598/31 test box to wiring
harness leading to engine control module;
engine control module should not be connected:

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24


If the wiring is OK: - Check for open circuit and short to positive or Ground in following
wiring connection: Connector
Contact
Test box VAG 1598/31
2 105
- Repair any open/short circuit as necessary.
- Replace engine control module.
Pa
ge 22 of 34 Char
ge pressure leak test with VAG 1687
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yp
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21-36

Checking power supply

Test requirements:

Fuse for wastegate bypass regulator valve
OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Fuel pump relay OK.

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24


- Connect voltage tester VAG 1527 B as follows:Connector
contact
Measure to
1 Engine Ground
- Operate starter briefly.

LED must light up.
Pa
ge 26 of 34 Char
ge pressure leak test with VAG 1687
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play?action=Goto&t
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pair&id=AUDI.B5.GE06.21.2

21-38
If the LED lamp does not flash or if it lights up
continuously:

- Connect VAG 1598/31 test box to wiring
harness leading to engine control module;
engine control module should not be connected:

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24


If the wiring is OK: - Check for open circuit and short to positive or Ground in following
wiring connection: Connector
Contact
Test box VAG 1598/31
2 104
- Repair any open/short circuit as necessary.
- Replace engine control module.
Pa
ge 29 of 34 Char
ge pressure leak test with VAG 1687
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
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pair&id=AUDI.B5.GE06.21.2

21-40

Test requirements:

Vehicle diagnostic, testing and information
system VAS 5051 or VAG 1551Scan Tool
connected.

Test sequence

Note:
The Charge Air Pressure sensor -G31- and the
wiring connections are monitored by the engine
control module.

- Read Diagnostic Trouble Code (DTC) memory
of engine control module.
If a DTC relating to the Charge Air Pressure
sensor -G31- is displayed:

Checking power supply

- Disconnect connector -arrow- on charge pressure sender.
Pa
ge 31 of 34 Char
ge pressure leak test with VAG 1687
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21-42


If specified value is attained:
Checking signal wire - Check for open circuit and short to positive or Ground in following
wiring connections: Connector
contact
Test box VAG 1598/31
1 108
3 98
- Repair any open/short circuit as necessary.
- Attach connector from charge air pressure sensor.
- Attach multimeter for voltage test to socket 101 and socket 108 of test
box.
- Start engine and run at idling speed.
Specified value: approx. 1.90 V
- Bring engine to speed by spontaneous acceleration.Specified value: 2.00...3.00 V
Pa
ge 33 of 34 Char
ge pressure leak test with VAG 1687
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE06.21.2