1995 AUDI A4 check engine

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,
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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
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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.
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11/21/2002 htt
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play?action=Goto&t
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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
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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