Page 1 of 65

28-1
 
     
Ignition system, checking 
     
General notes on ignition system
 
     
The battery should only be disconnected and 
reconnected when the ignition is turned off, 
since otherwise the Engine Control Module 
(ECM) can be damaged. 
     The Engine Control Module (ECM) is equipped 
with an On Board Diagnostic (OBD) 
     For the electric components to work properly, a 
voltage of at least 12.7 V is required. 
     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. 
     If the engine only starts briefly and then turns 
off again after troubleshooting, repair or 
checking of the components, it may be that the 
immobilizer is blocking the Engine Control 
Module (ECM). DTC memory must then be 
checked and if necessary, control module must 
be adapted. 
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        Page 18 of 65
28-15
       Component location   Overview of Component 
Locations, page   Page 24
-5   
     
Test sequence  
     
-  Connect VAS5051 tester or VAG1551 scan tool 
and select the control module for engine 
electronics using "address word" 01   Page 01
-
9 . 
     
   Ignition must remain switched on for this.Rapid data transfer  
HELP
Select function XX
    
When indicated on display:  
-  Press buttons -0- and -8- to select "Read Measuring Value Block" and 
press -Q- button to confirm input. 
Read Measurin
g Value Block 
Q
Input display group number XXX
    
When indicated on display:  
-  Press buttons -0-, -0- and -4- to select "display group number 004" and 
press -Q- button to confirm input. 
Read Measuring Value Block 4  
1 
2 
3 
4
    
Indicated on display:  
-  Check specified value for Intake Air Temperature (IAT) sensor in 
display field 4: 
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        Page 27 of 65
28-24
       Component location   Overview of Component 
Locations, page   Page 24
-5   
     
Test requirement:  
     
Engine cold 
     
Test sequence  
     
-  Connect VAS5051 tester or VAG1551 scan tool 
and select the control module for engine 
electronics using "address word" 01   Page 01
-
9 . 
     
   Engine must run at idle for this.Rapid data transfer  
HELP
Select function XX
    
When indicated on display:  
-  Press buttons -0- and -8- to select "Read Measuring Value Block" and 
press -Q- button to confirm input. 
Read Measurin
g Value Block 
Q
Input display group number XXX
    
When indicated on display:  
-  Press buttons -0-, -0- and -4- to select "display group number 004" and 
press -Q- button to confirm input. 
Read Measuring Value Block 4  
1 
2 
3 
4
    
Indicated on display:  
-  Check indication in display field 3.
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        Page 39 of 65
28-34
      
Check ignition angle retardation of the 
individual cylinders  
     
-  Connect VAS5051 tester or VAG1551 scan tool 
and select the control module for engine 
electronics using "address word" 01   Page 01
-
9 . 
     
   Engine must run at idle for this.Rapid data transfer  
HELP
Select function XX
    
When indicated on display:  
-  Press buttons -0- and -8- to select "Read Measuring Value Block" and 
press -Q- button to confirm input. 
Read Measuring Value Block 
Q
Input displa
y group number XXX
    
When indicated on display:  
-  Press buttons -0-, -2- and -0- to select "display group number 020" and 
press -Q- button to confirm input. 
Read Measuring Value Block 20  
1 
2 
3 
4
    
When indicated on display:  
-  Check indication in all display fields.
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        Page 40 of 65

28-35
 
  
Display fields  
  
1   2   3   4  
Display group 020: Ignition -knock control in driving operation  
Display  
xx.x  KW  
xx.x  KW  
xx.x  KW  
xx.x  KW  
Indicated  
Ignition angle 
retardation cylinder 1 
via knock control 
Knock sensor control  Ignition angle 
retardation cylinder 2 
via knock control 
Knock sensor control  Ignition angle 
retardation cylinder 3 
via knock control 
Knock sensor control  Ignition angle 
retardation cylinder 4 
via knock control 
Knock sensor control  
Specified 
value  0 to 12  KW  
0 to 12  KW  
0 to 12  KW  
0 to 12  KW  
Notes  Evaluation  Page 28
-40
   
Note:  
The number values indicated in display fields 1 to 4 represent actual ignition angle retardation via knock control of the 
individual cylinders. Ignition angle retardation occurs in  KW (crankshaft degrees) toward retardation.      
- Press -C- button.Read Measuring Value Block 
Q
Input display group number XXX
    
When indicated on display:  
-  Press buttons -0-, -2- and -1- to select "display group number 021" and press -
Q- button to confirm input. 
Read Measuring Value Block 21  
1 
2 
3 
4
    
When indicated on display:  
-  Check indication in display field 1 and 2.
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        Page 41 of 65

28-36
 
  
Display fields  
  
1   2   3   4  
Display group 021: Ignition -knock control in driving operation  
Display  
xx.x  KW  
xx.x  KW  
  
  
Indicated  
Ignition angle retardation cylinder 5 via 
knock control 
Knock sensor control  Ignition angle retardation cylinder 6 via 
knock control 
Knock sensor control    
  
Specified 
value  0 to 12  KW  
0 to 12  KW  
  
  
Notes  Evaluation  Page 28
-40
   
  
  
Note:  
The number values indicated in display fields 1 and 2 represent actual ignition angle retardation via knock control of the 
individual cylinders. Ignition angle retardation occurs in  KW (crankshaft degrees) toward retardation.      
- Press -C- button.Read Measurin
g Value Block 
Q
Input displa
y group number XXX
    
When indicated on display:  
-  Press buttons -0-, -2- and -2- to select "display group number 022" and press -Q-
button to confirm input. 
Read Measuring Value Block 22  
1 
2 
3 
4
    
When indicated on display:  
-  Check indications in display field 3 and 4.
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        Page 42 of 65

28-37
 
  
Display fields  
  
1   2   3   4  
Display group 022: Ignition -knock control in driving operation  
Display   xxxx/min   xxx.x %  
xx.x  KW  
xx.x  KW  
Indicated  Engine speed 
(RPM)  Engine 
load  Ignition angle retardation cylinder 1 
via knock control 
Knock sensor control  Ignition angle retardation cylinder 2 
via knock control 
Knock sensor control  
Specified 
value  xxxx/min   12 to 100 
%  0 to 12  KW  
0 to 12  KW  
Notes        Evaluation  Page 28
-40
   
Note:  
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders 
1 and 2. Ignition angle retardation occurs in  KW (crankshaft degrees) toward retardation.      
- Press -C- button.Read Measurin
g Value Block 
Q
Input displa
y group number XXX
    
When indicated on display:  
-  Press buttons -0-, -2- and -3- to select "display group number 023" and press -Q-
button to confirm input. 
Read Measuring Value Block 23  
1 
2 
3 
4
    
When indicated on display:  
-  Check indications in display field 3 and 4.
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        Page 43 of 65

28-38
 
  
Display fields  
  
1   2   3   4  
Display group 023: Ignition -knock control in driving operation  
Display   xxxx/min   xxx.x %  
xx.x  KW  
xx.x  KW  
Indicated  Engine speed 
(RPM)  Engine 
load  Ignition angle retardation cylinder 3 
via knock control 
Knock sensor control  Ignition angle retardation cylinder 4 
via knock control 
Knock sensor control  
Specified 
value  xxxx/min   12 to 100 
%  0 to 12  KW  
0 to 12  KW  
Notes        Evaluation  Page 28
-40
   
Note:  
The number values indicated in display fields 3 and 4 represent actual ignition angle retardation via knock control of cylinders 
3 and 4. Ignition angle retardation occurs in  KW (crankshaft degrees) toward retardation.      
- Press -C- button.Read Measurin
g Value Block 
Q
Input displa
y group number XXX
    
When indicated on display:  
-  Press buttons -0-, -2- and -4- to select "display group number 024" and press -Q-
button to confirm input. 
Read Measuring Value Block 24  
1 
2 
3 
4
    
When indicated on display:  
-  Check indications in display field 3 and 4.
Pa
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