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Checking Lambda probe heating after catalyst > < Checking components

Leon Mk2

Checking Lambda probe heating before catalyst
Checking Lambda probe heating before catalyst
Special tools and workshop equipment required
t  Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with cable -V.A.G 1551/3A-
t  Test box -V.A.G 1598/22-
t  Hand multimeter -V.A.G 1526- or multimeter -V.A.G 1715-
t  Adapter set -V.A.G 1594-
t  Current flow diagram
Check conditions
   
l  All fuses must be OK.
l  The battery voltage must be at least 11.5 V.
l  Fuel pump relay must be OK
Test sequence
–  Connect fault reader -V.A.G 1551- (-V.A.G 1552-). Start engine and select “Address word” 01 of engine control unit. When doing this the engine must be running at idling speed. (Connecting fault reader and selecting engine control unit → Vehicle diagnosis, testing and information system VAS 5051.)
  N24-0831
Indicated on display:
–  Press keys 0 and 8 for the function “Read measured value block” and confirm entry with Q key.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Press keys 0, 4 and 1 for “Display group number 41” and confirm entry with Q key.
  
Read measured value block               
Input display group number XXX
Indicated on display: (1...4 = Display zones)
–  Check status of Lambda probe heating before catalyst in display zone 2: Display: Htg.bC.ON
  Note!
The Lambda probe heating may be switched on or off depending on the operating mode of the engine, therefore the display in display zone 2 may show "Htg.bC.ON or alternating from Htg.bC.ON to Htg.bC.OFF.
If the specification is obtained:
–  Press → key.
–  Press keys 0 and 6 for the function “End output” and confirm entry with the Q key.
–  Switch off ignition.
If the specification is not obtained:
Only engine codes ANV, AUC, AUD, ANW
Engine code ALD → Anchor
  
Read measured value block 41           →

      

      

    
      

      

    
– 
          Separate 6-pin connector (black) to Lambda probe before catalyst -G39--arrow-.
– 
          Set multimeter to “Resistance measurement” range.

      		 
      
    N24-0917
      

      

    
      

      

    
– 
          Check probe heating resistance at connector to Lambda probe contacts 3 and 4 Specification: 2,5...10 Ω (at room temperature).
If it is determined that probe heating has an open circuit:
– 
          Replace the Lambda probe before catalyst -G39-.
– 
          Erase learnt values and adapt engine control unit  → Chapter
If probe heating has continuity:
Checking voltage supply

      		 
      
    N24-1279
      

      

    
      

      

    
– 
          Connect the Multimeter with aux. cables from -V.A.G 1594- to measure voltage on contacts 3 + 4 (connector to engine control unit).
– 
          Start engine and run at idling speed.
– 
          Measure the voltage supply: When display group 41, display zone 2 displays Display, Htg.bC.ON: Specification: 11.0...14.5 V Display, Htg. bC.ON/Htg.bC.OFF (alternating) Specification: Between 0,0...12.0 V fluctuating
– 
          Press → key.
– 
          Press keys 0 and 6 for the function “End output” and confirm entry with the Q key.
– 
          Switch off ignition.
If no voltage is present:
– 
          Remove wiper arms and cowl panel:  → Electrical system; Rep. Gr.92

      		 
      
    M24-0057
      

      

    
      

      

    
– 
          Connect test box -V.A.G 1598/22- to control unit wiring harness.

      		 
      
    N24-0709
      

      

    
      

      

    
– 
          Check wire between test box and 6-pin connector (connector to control unit) for open circuit using current flow diagram. Contact 4+socket 1 Wire resistance: max. 1.5 Ω
If the specification is obtained:
– 
          Check wire between 6-pin connector contact 3 and fuel pump relay -J17- for open circuit using current flow diagram. Wire resistance: max. 1.5 Ω
Only engine code ALD, AKK

      		 
      
    M24-0056
      

      

    
      

      

    
– 
          Separate 4-pin connector (black) to Lambda probe before catalyst -G39--arrow-.

      		 
      
    N24-0917
      

      

    
      

      

    
– 
          Check probe heating for continuity at Lambda probe connector contacts 1 + 2.
 
      Note!
The heater element resistance is approx. 1...5 Ω at room temperature. Even slight increases in room temperature increase the resistance greatly.
If it is determined that probe heating has an open circuit:
– 
          Renew Lambda probe before catalyst -G39- → Item.
If probe heating has continuity:
Checking voltage supply
– 
          Set multimeter to “Voltage measurement” range.

      		 
      
    N24-0721
      

      

    
      

      

    
– 
          Connect multimeter using aux. cables from -V.A.G 1594- to measure voltage at contacts 1+2 (connector to engine control unit).
– 
          Start engine and run at idling speed. Specification: 11.0...15.0 V
– 
          Switch off ignition.
If no voltage is present:

      		 
      
    N24-0722
      

      

    
      

      

    
– 
          Check wiring between 4 pin connector contact 2 and engine earth for open circuit Wire resistance: Max. 1.5 Ω
If the specification is obtained:
– 
          Check wire between 4 pin connector contact 1 and fuel pump relay -J17- for open circuit using current flow diagram. Wire resistance: max. 1.5 Ω

      		 
      
    N24-0723
      

      

    


Checking Lambda probe heating after catalyst >
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