01-3
      
Malfunction Indicator Lamp (MIL), 
significance
 
      If the ECM recognizes malfunctions that lead to a 
degradation of emissions values, it indicates 
them by lighting the Malfunction Indicator Lamp 
for exhaust.  
    
Installation position of exhaust MIL  
Note:  
The Malfunction Indicator Lamp (MIL) can blink or remain lit continuously. 
DTC memory should be checked in both cases   Page 01
-15
 . 
Blinking: There is a malfunction that causes damage to the catalytic 
converter in this driving condition (e.g. combustion misfire). In this 
case, vehicle must only be driven at reduced power! Continuously lit: There is a malfunction that causes increased 
emissions. Check DTC memory for Motronic ECM and automatic 
transmission (if installed). If there are driveability problems or if there is a customer complaint 
and the exhaust MIL is not lit, DTC memory must be checked. There 
may be DTCs stored that do not cause the exhaust MIL to light up 
immediately, but only if malfunction is recognized again after repeated 
engine starts. 
Pa
ge 3 of 19 Motronic, On Board Dia
gnostic 
(OBD
)
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.01.1 
01-9
      
VAS 5051 vehicle diagnostic, testing 
and information system orVAG1551 
Scan Tool (ST), connecting and 
selecting functions
 
     
Test requirements:  
     
Fuses for engine electronics OK 
     
       Electrical Wiring Diagrams, Troubleshooting & 
Component Locations binder   
     
Fuel Pump (FP) OK, checking   Page 24
-
49
 . 
     
Battery voltage at least 12.7 V 
     Ground (GND) connections at engine and 
transmission OK 
     
Procedure  
    
Note:   -  Connect VAS5051 tester to vehicle with VAS5051/1 diagnostic wire. 
Alternately, VAG1551 Scan Tool (ST) can also be attached using 
VAG1551/3B cable. 
Pa
ge 11 of 19 Motronic, On Board Dia
gnostic 
(OBD
)
11/23/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU05.01.1