1999 AUDI A4 check engine

24-2

It is possible that the control module will
recognize a malfunction and store a DTC during
some tests. After completing all tests and
repairs, DTC memory should therefore be
checked and erased if necessary. Readiness
code must be generated after DTC memory is
erased Page 01
-84
.

Always switch ignition off before cleaning
engine.
The battery should only be disconnected and
reconnected when the ignition is turned off,
since otherwise the Engine Control Module
(ECM) can be damaged.

WARNING!

Fuel system is under pressure! Before
opening system, place rags around the
connection point. Then release pressure by
carefully loosening connection.
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24-6


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AWM, Engine Code(s): AWM, Repair Group 26; Secondary Air Injection (AIR) system, checking
3 -
Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC) -G130-, 55 Nm
Check Oxygen Sensor (O2S) and oxygen
sensor control behind Three Way Catalytic
Converter (TWC) Page 24
-94

Check oxygen sensor heater for Oxygen
Sensor (O2S) behind Three Way Catalytic
Converter (TWC) Page 24
-107

Removing and installing Page 24
-112
4 -
Combination valve for secondary air
injection (AIR)
Checking, removing and installing:
5 -
Engine Coolant Temperature (ECT) sensor
-G62-
Checking Page 28
-31
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24-7


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AWM, Repair Group 26; Secondary Air Injection (AIR) system, checking

6 -
Fuel pressure regulator
Checking Page 24
-32
7 -
Engine Speed (RPM) sensor -G28-
Checking Page 28
-27
8 -
Secondary Air Injection (AIR) solenoid
valve-N112-
Installation location Fig. 4
, Page
24
-14

Checking:Green harness connector
9 -
Bracket for harness connectors Component location Fig. 1
, Page
24
-13

Accessible with coolant expansion tank
unbolted and swung to the side.
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24-9


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AWM, Repair Group 26; Secondary Air Injection (AIR) system, checking

13 -
E-box, plenum chamber
Installation locations Fig. 6
, Page
24
-15

Installation location for motronic Engine
Control Module (ECM) -J220- with
integrated Barometric pressure (BARO)
sensor -F96- Check voltage supply of Engine Control
Module (ECM) Page 28
-37

Procedure to follow after open circuit in
voltage supply Page 24
-21

Replacing Engine Control Module (ECM)
Page 24
-22

Installation location of Secondary Air
Injection (AIR) pump relay -J299- Check Secondary Air Injection (AIR) pump
relay -J299-: Installation location of motronic Engine
Control Module (ECM) voltage supply relay
-J271- Check motronic Engine Control Module
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24-10


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AWM, Repair Group 21, Charge air system with turbocharger, checking
14 -
Clutch vacuum vent valve switch -F36-
Component location Fig. 3
, Page
24
-14

15 -
Charge air pressure sensor -G31-
Installation location Fig. 7
, Page
24
-16

Checking:
16 -
Throttle valve control module -J338-
With throttle drive (power accelerator
actuation) -G186-, angle sensor -1- for
throttle drive (power accelerator actuation)
-G187-, and angle sensor -2- for throttle
drive (power accelerator actuation) -G188- Checking Page 24
-124
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24-12


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AWM, Repair Group 21, Charge air system with turbocharger, checking

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AWM, Repair Group 26; Secondary Air Injection (AIR) system, checking

23 -
Ignition coil
Ignition coil -N-Ignition coil 2 -N128-Ignition coil 3 -N158-Ignition coil 4 -N163-Checking Page 28
-4
24 -
Wastegate bypass regulator valve -N75-
Checking:
25 -
Mass Air Flow (MAF) sensor -G70-
Checking Page 24
-59
26 -
Secondary Air Injection (AIR) pump
motor-V101-
Checking:
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24-27

Notes:

Idle speed cannot be adjusted.
Idle speed is checked during basic setting of
the engine.
During basic setting, the Evaporative Emission
(EVAP) canister purge regulator valve (EVAP
valve -N80-) is closed and the A/C compressor
is switched off

Test sequence

- Check DTC memory Page 01
-12
. There must
not be any DTCs stored, repair malfunctions if
necessary, erase DTC memory, switch engine
off and start again, road test vehicle and check
DTC memory again as a control measure.

- Let engine continue to run at idle.

WARNING!

The electric fan for the radiator must not be
running.
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24-29


Display on VAS5051:
- Check whether the engine speed in display field -1 (actual engine
speed) is within the permissible specified range.

Display fields

1 2 3 4
Display group 056: Idle stabilization at operating temperature
Display
xxx /min
xxx /min x.x % X X X X X
Indicated
Engine speed (actual)
Engine speed
(specified) Idle control
Torque
change Operating conditions
Specified
value FWD: 740 to 860 RPM
AWD: 760 to 880 RPM FWD: 800 RPM
AWD: 820 RPM x.x % 0 0 0 0 0
Note
If specified value is not obtained
Page 24
-31

Significance of numbers
Page 24
-31
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