1996 AUDI A4 ECO

01-3
Modes under address word 33:
Mode 1: Transfer diagnosis data Switch ignition on or let engine idle
Mode 2: Transfer operating conditions Switch ignition on or let engine idle
Mode 3: Check DTC memory Switch ignition on or let engine idle
Mode 4: Erase diagnosis information Switch ignition on or let engine idle
Mode 5: Output of HO2S signals Switch ignition on or let engine idle
Mode 6: Read test results (starting with control module 8D0 906 266 A) Switch ignition on or let engine idle
Mode 7: Read test results (starting with control module 8D0 906 266 A) Switch ignition on or let engine idle

Under address word 33, Mode 1 to Mode 5 can be selected starting from control module 8D0 906 266 and Mode 1 to
Mode 7 starting from control module 8D0 906 266 A.
Individual measuring values can be read under Mode 1. This is not recommended for Audi service department since this
information is available more easily under address word 01, function 04 and/or function 08.
Mode 2 shows the operating conditions under which a malfunction was recognized.
Mode 3 is used to check the DTC memory and Mode 4 is used to erase the DTC memory. In the Audi service department,
only address word 01, function 05 should be used to erase, since with Mode 4 the DTC memory is erased immediately
even if it was not checked first.
Static variables of HO2S probes, required by legal regulations, are displayed under Mode 5. Since these variables have
no direct relationship to HO2S diagnosis, Mode 5 is not needed by the Audi service department.
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01-4

Malfunction Indicator Lamp (MIL),
functions


Functional testing:
The Malfunction Indicator Lamp (MIL) must light up every time the
ignition is switched on and go out after the engine starts. If a
malfunction is recognized by the engine control module or the
transmission control module, this is indicated by the MIL lighting up. If the MIL lights up continuously, there is a malfunction present that
makes the exhaust gas worse. In this case, the DTC memory for the
engine control module and/or the transmission control module should
be checked. If the MIL starts to blink, there is a malfunction that can lead to
damage of the three way catalytic converter (e.g. combustion misfiring
with high misfiring rate). In this case, driving should only continue with
reduced power (until the MIL goes off or lights up continuously) and
the malfunction should be eliminated as quickly as possible.
- Switch ignition on: the MIL must light up. If the MIL does not light up,
check wiring according to wiring diagram and/or replace lamp.
- Start engine and let idle: MIL must go out after a couple seconds. If the
MIL does not go out after the engine starts, check DTC memory for the
engine and/or transmission control modules (malfunctions in DTC
memory).
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01-5
Malfunction recognition and repair

Notes:

Before initiating the On Board Diagnostic (OBD) program, and before testing wiring and replacing components, check the
following ground connections for corrosion and damaged connections and repair them if necessary
- Check ground connections on intake manifold
- Battery ground strap OK
- Ground cable between engine and body OK Malfunction recognition and repair is described for the VAG 1551 scan tool, since it offers significantly more functions.
However, malfunction recognition and repair is also possible with a "generic" scan tool.
A specific procedure must be used to evaluate malfunctions, since the engine electronics can be checked with address
word 01 and address word 33 on OBD II vehicles. Address word 33 can only be used to check malfunctions that have
already switched on the Malfunction Indicator Light (MIL). Address word 01 can also display the malfunctions that have
not switched on the MIL. In contrast to before, the MIL is not switched on immediately with some malfunction types, but
only after two successive trips with cold starts preceding them where the malfunction occurs. If there is a customer
complaint and/or driving performance problem, the DTC memory should be checked thoroughly with address word 01,
function 02. On vehicles with MIL lit up, the DTC memory should also be checked with address word 33, mode 3. If the
DTC memory is checked with mode 3, mode 2 should also be checked which shows the operating conditions as they were
when the malfunction was recognized.
If a malfunction is present for longer than a specified time, the malfunction is stored as a static malfunction. Malfunctions
that never or immediately switch the MIL on are set as "sporadic" at each engine start. If the malfunction occurs again, the
"sporadic" status is erased again. The "sporadic" status is erased exclusively after an OK diagnosis for malfunctions that
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01-6

The MFI control module differentiates among approx. 150 different malfunctions after evaluating the information, and
stores them until the DTC memory is erased Diagnostic Trouble Code (DTC) table, page 01
-26
.
If possible, the DTC memory should be checked with engine running.
If no malfunction is stored in the DTC memory, do not additionally erase DTC memory with function 05 since the readiness
code (if it has been set) will be erased.
The DTC memory should only be erased with function 05 since the DTC memory is erased immediately with mode 4 even
if the DTC memory was not checked before that.
If a malfunction recognized by the On Board Diagnostic (OBD) is eliminated, the following work steps should be carried
out after that:
- Erase DTC memory
- Stop engine (switch ignition off) and start it again
- Take a test drive
- Carry out automatic test sequence by inserting address word 00 Note:
Every time the DTC memory is erased (both with function 05 and with mode 4), the readiness code is reset.
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01-9

For the function:

02: Check DTC
Memory - Let engine idle, or, crank
engine with starter for at
least 5 seconds without
switching ignition off
03: Output
Diagnostic
Test Mode - Switch ignition on
04: Basic Setting
- Let engine run or switch
ignition on
07: Code Control
Module - Switch ignition on
08: Read
Measuring
Value Block - Let engine run or switch
ignition on

- Switch printer on with PRINT button (indicator
light in the button lights up).

- Press button -1- for "rapid data transfer"
operating mode.
Rapid data transfer
HELP
Insert address word XX

Indicated on display
Note:
After inserting address word 00 and pressing -Q- button to confirm input,
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01-13

DTC memory, checking and erasing


- Connect VAG 1551 scan tool and operate until
the display shows "Select function XX" page
01
-7 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -2- to select the"Check DTC Memory" function
02.
Rapid data transfer
Q
02 - Check DTC Memor
y

Indicated on display
- Press -Q- button to confirm input.
X DTC reco
gnized

The number of stored Diagnostic Trouble Codes (DTC) or "No DTC
recognized" is shown on the display.
Notes:
No DTC reco
gnized

Note:
If there is a complaint that is not recognized by the On Board Diagnostic
If the printer is switched on, the stored malfunctions will be displayed
and printed out in sequence. If the printer is switched off, the button must be pressed to display
the next malfunction.
-
After the last malfunction is displayed, press the button.
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01-16
Diagnostic Trouble Code (DTC) overview

Notes:

The Diagnostic Trouble Code (DTC) overview is organized according to SAE and VAG trouble codes.
Diagnostic Trouble Codes (DTC) for which the MIL is not switched on by the engine control module after a malfunction is
recognized are identified with the MIL switching condition "off."
Diagnostic Trouble Codes (DTC) for which the MIL is switched on by the engine control module immediately after a
malfunction is recognized are identified with the MIL switching condition "immediately."
Diagnostic Trouble Codes (DTC) for which the MIL is not switched on until the malfunction is recognized after taking 2
trips (FTP 72) are identified with the MIL switching condition "2 Trips."
Always repair the malfunctions with the MIL switching condition "immediately" first, and then the malfunctions with the
switching condition "2 Trips."
Diagnostic Trouble Code
(DTC) Malfunction text
MIL switching
condition
SAE
VAG
P0102 16486 Mass or Volume Air Flow Circuit Low Input immediately
P0103 16487 Mass or Volume Air Flow Circuit High Input immediately
P0116 16500 Engine Coolant Temperature Circuit Range/Performance
Problem immediately
P0117 16501 Engine Coolant Temperature Circuit Low Input immediately
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01-26
Diagnostic Trouble Code (DTC) table


Following are all the possible malfunctions that can be recognized by the Engine Control Module (ECM) -J192- and
printed on the VAG 1551 scan tool printer, listed according to code identifier ( SAE and VAG codes).
Malfunctions that switch the MIL on never or immediately are set as "sporadic" each time the engine is started. If the
malfunction occurs again, the "sporadic" status is set again. For malfunctions that only switch the MIL on after two trips
with malfunction, the "sporadic" status is only erased after an OK diagnosis.
If the MIL lights up with engine running, there is a malfunction that makes the exhaust gas worse. If the MIL lights up and
the engine is running, there must in any case be a malfunction stored in the DTC memory of the engine control module
and/or of the transmission control module. In this case, the DTC memory of the engine control module and/or the
transmission control module must be checked.
If the MIL starts to blink, there is a malfunction present that can lead to three way catalytic converter damage (e.g.
combustion misfiring with high misfiring rate). In this case, the trip should be continued with reduced power (until the MIL
goes out or lights up continuously) and the malfunction should be eliminated as quickly as possible.
The malfunction is not stored in the DTC memory immediately and the MIL is not switched on immediately with some
malfunction types, but only after two successive trips with or without preceding cold start (-10 to 30 C (14 to 86 F)
and malfunction occurring (malfunction recognition twice). The MIL switching condition is always specified in the Diagnostic Trouble Code (DTC) table.
Combustion misfiring with high misfiring rate is displayed immediately with the MIL blinking, since the three way catalytic
converters can be damaged. In this case, driving should continue only with reduced power and the malfunction should be
eliminated as soon as possible.
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