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
-73
.

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): AEB, ATW, 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
-87

Check oxygen sensor heater for Oxygen
Sensor (O2S) behind Three Way Catalytic
Converter (TWC) Page 24
-99

Removing and installing Page 24
-105
4 -
Combination valve for secondary air
injection (AIR)
Checking, removing and installing:
5 -
Engine Coolant Temperature (ECT) sensor
-G62-
Checking Page 28
-30
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24-7


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AEB, ATW, Repair Group 26; Secondary Air Injection (AIR) system, checking
6 -
Fuel pressure regulator Checking Page 24
-33
7 -
Engine Speed (RPM) sensor -G28-
Checking Page 28
-26
8 -
Secondary Air Injection (AIR) solenoid
valve-N112-
Installation position Page 24
-14
, Fig.
4
Checking:Green harness connector
9 -
Bracket for harness connectors Component location Page 24
-13
, Fig.
1

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): AEB, ATW, Repair Group 26; Secondary Air Injection (AIR) system, checking
13 -
E-box, plenum chamber Installation locations Page 24
-15
, Fig.
6

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
-36

Procedure to follow after open circuit in
voltage supply Page 24
-22

Replacing Engine Control Module (ECM)
Page 24
-23

Installation location of Secondary Air
Injection (AIR) pump relay -J299- Check Secondary Air Injection (AIR) pump
relay -J299-:
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24-10


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

Installation location of motronic Engine Control
Module (ECM) power supply relay -J271-
Check motronic Engine Control Module (ECM)
power supply relay -J271- Page 28
-13

Installation location of fuse S130 for Secondary
Air Injection (AIR) pump
14 -
Clutch vacuum vent valve switch -F36-
Component location Page 24
-14
, Fig.
3

15 -
Charge air pressure sensor -G31-
Installation position Page 24
-16
, Fig.
7
Checking:
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24-12


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

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Engine
Mechanical, Engine Code(s): AEB, ATW, Repair Group 26; Secondary Air Injection (AIR) system, checking
22 -
Fuel injectors -N30- through -N33- Checking Page 24
-38
Removing and installing Page 24
-46
23 -
Ignition coils -N-, -N128-, -N158-, -N163-
Checking Page 28
-4
24 -
Wastegate bypass regulator valve -N75-
Checking:
25 -
Mass Air Flow (MAF) sensor -G70-
Checking Page 24
-60
26 -
Secondary Air Injection (AIR) pump
motor-V101-
Checking:
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24-21

Note:
Important note:
After re-connecting the Engine Control Module
(ECM), the following work steps must be
performed:
- Perform adaptation of the Throttle Valve Control
Module -J338- Page 24
-121
.
- For vehicles with automatic transmission, the
kick down function must be adapted Page 24
-
139
.
- Check DTC memory and erase it if necessary
Page 01
-16
.
- If DTC memory was erased, readiness code
must be re-generated Page 01
-73
.

Note:
During the first adaptation phase, it is possible
that idle will be rough and vehicle may shake
lightly in drive mode.
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24-26

Installing
Installation is reverse of removal, noting the
following:

Note:
Important note:
After installing new Engine Control Module
(ECM), the following work steps must be
performed:
- Check DTC memory and erase it if necessary
Page 01
-16
.
- Perform adaptation of the Throttle Valve Control
Module -J338- Page 24
-121
.
- Observe notes for coding new Engine Control
Module (ECM) Page 01
-62
.
- For vehicles with cruise control (discernable at
steering column), switch this free in ECM:

Repair Manual, Electrical Equipment On
Board Diagnostic (OBD), Repair Group 01; OBD for cruise control system

- For vehicles with automatic transmission, the
kick down function must be adapted Page 24
-
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