24-72
      
Checking voltage supply to Mass Air Flow 
(MAF) sensor  
     
-  Disconnect harness connector from air mass 
meter. 
    
Note:  
The mass air flow sensor receives its voltage supply via the fuel pump 
relay. 
If the reading does not match the battery voltage:  
 Electrical Wiring Diagrams, Troubleshooting & Component Locations    -  Connect hand-held multimeter (voltage measurement range) between 
engine Ground (GND) and socket 2 of connector. 
-  Operate starter briefly. 
   Specification: approx. battery voltage
-  Check for open circuit or short to Ground (GND) in wiring between fuel 
pump relay and socket 2 on connector via fuse. Repair if necessary. 
Pa
ge 83 of 90 Motronic Multi
port Fuel In
jection 
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1 
         
        
        24-73
 
    
Note:  
Socket 3 on the connector is the Ground (GND) connection from the 
engine control module. 
If the specification is not attained:  -  Connect hand-held multimeter (voltage measurement range) between 
sockets 2 and 3 of connector. 
-  Operate starter briefly. 
   Specification: approx. battery voltage
- Check wiring   Page 24
-74
 .
    
If the specification is not attained:  -  Connect hand-held multimeter (voltage measurement range) between 
sockets 3 and 4 of connector. 
-  Switch ignition on.
   Specification: approx. 5 V 
- Check wiring   Page 24
-74
 .
Pa
ge 84 of 90 Motronic Multi
port Fuel In
jection 
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1