check engine AUDI A4 1995 B5 / 1.G AWM Engine Charge Air Syst

21-9

Test requirements:

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

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 01


All hoses and lines must be checked for
correct seating and leaks.
Diagnostic Trouble Code (DTC) memory has
been checked:

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 01


Output Diagnostic Test Mode (DTM) has
been performed:

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM,
Pa
ge 9 of 17 Char
ge air s
ystem with turbochar
ger, checkin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE06.21.1

21-12

Read measured value block 115
1
2
3
4

Note:
The charge pressure level is measured with turbocharger tester VAG
1397/A. The vehicle diagnostic, measuring and information system VAS
5051 or the VAG 1551 Scan Tool is used to check whether the charge
pressure is being registered by the control module. - Read measured value block Display group 115, engine idling.
- Accelerate vehicle from 2000 rpm at wide open throttle in third gear,
and observe rev counter.
- At approx. 2500 rpm press print key on VAS 5051 or PRINT key on
VAG 1551 and at same time press recall button -M- on VAG 1397 A.

Specified value on VAG 1397 A: 1.700 to 1.800 bar
Read measured value block 115
1
2
3
4

If specified value not attained table, Page 21
-13

Specified value on VAG 1551 or on VAS 5051 in display zone 4: 1700
to 1800 mbar
Pa
ge 13 of 17 Char
ge air s
ystem with turbochar
ger, checkin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE06.21.1

21-13
Charge air pressure control malfunctions Malfunction
Possible causes
Charge air pressure below
specified value
Wastegate Bypass Regulator valve -N75- faulty checking, Page 21
-33
Hose connection to Wastegate Bypass Regulator valve -N75- faulty Connection
diagram, Page 21
-3
Wastegate bypass regulator valve in turbocharger stuck openLeak between exhaust turbocharger and intake hose Effects, Page 21
-14
Mechanical air recirculation valve faulty checking, Page 21
-24
Recirculating valve for turbocharger -N249- faulty checking, Page 21
-26
Exhaust turbocharger faulty replacing, Page 21
-51
Charge air pressure above
specified value
1)
Vacuum unit for wastegate bypass regulator valve faulty Replacing exhaust
turbocharger, Page 21
-51

Hose connection to vacuum unit for charge air pressure limiter (above -N75-) leaks
Connection diagram, Page 21
-3
When in closed position wastegate bypass regulator valve in exhaust turbocharger
sticks replacing exhaust turbocharger, Page 21
-51

1) If the charge air pressure is too high the fuel supply will be interrupted in order to protect the engine. This results in misfiring
at high engine speeds.
Pa
ge 14 of 17 Char
ge air s
ystem with turbochar
ger, checkin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE06.21.1

21-15

Leak downstream of exhaust turbocharger

Effect: Charge pressure too low

Possible malfunction sources:

1 - Connection hoses and line between exhaust
turbocharger and charge air cooler

2 - Hose between charge air cooler and intake
line

3 - Charge air cooler

4 - Seal of Charge Air Pressure sensor -G31- (in
charge air cooler)

5 - Sealing between throttle valve control
module and intake line

6 - Sealing between intake line and cylinder
head

Effects of leaks on exhaust side
Effect: Charge air pressure too low, possible
exhaust smell, soot traces in engine
compartment
Pa
ge 16 of 17 Char
ge air s
ystem with turbochar
ger, checkin
g
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE06.21.1