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Post catalyst lambda probe and regulation: testing > < Idling test

Leon Mk2

Pre-catalyst lambda probe and regulation: testing
   
Pre-catalyst lambda probe and regulation: testing
Special tools and workshop equipment required
t  Fault reader -V.A.G 1551- or Vehicle systems checker -V.A.G 1552- with Lead -V.A.G 1551/3B-
t  Test box -V.A.G 1598/22-
t  Hand-held multimeter -V.A.G 1526 A- or Multimeter -V.A.G 1715-
t  Auxiliary measurement set -V.A.G 1594 C-
t  Wiring diagram

Test conditions
   
l  Fuse number 18, OK.
l  Battery voltage, 11.5 V minimum
l  Exhaust system, airtight between the catalyst and cylinder head.
l  Coolant temperature, 80 °C minimum → Anchor, display field 3.
Function test
–  Connect the -V.A.G 1551- (V.A.G. 1552). Start the engine and enter “address code” 01 to select the engine control unit. (Fault reader: Connecting and selecting the engine control unit → Chapter.).
  E01-0119
The display reads:
–  Press 0 and 8 for the function “Read measurement value block” and press Q to confirm the entry.
  
Rapid data transmission             HELP
Select function XX
The display reads:
–  Press 0, 3 and 0 for “Display group number 30” and press Q to confirm the entry.
  
Read measurement value block        HELP
Enter display group number XXX
The display reads: (1...2 = display fields)
–  Test the state of the pre-catalyst lambda regulation (display field 1): Target value: 1 1 1 (Meaning → Anchor).
  Note!
t  The first position of the 3-digit numerical block switches temporarily between 0 and 1 (lambda probe heating ON and OFF).
t  Depending on the state of lambda regulation, the 3-digit numerical may alternate between 0 and 1.
t  The bits in the display field 1 change to 1 when the catalyst temperature is above 400.0 °C ( → Anchor, display field 2).
If the target value is not reached:
If the target value is reached:
–  Change to group 32 as follows:
–  Press C.
–  Press 0, 3 and 2 for “Display group number 32” and press Q to confirm the entry.
  
Read measurement value block 30       ->
                   1                   2
The display reads: (1...2 = display fields)
–  Check the lambda self-adaptation values at idling (additive) in display field 1. Target value: -10.0...10.0 %
–  Check the lambda self-adaptation values at half load (multiplicative) in display field 2. Target value: -10.0...10.0 %
If the target values are not reached: → Anchor, analysis display group 32.
If the target values are reached:
–  Change to group 33 as follows: -V.A.G 1551-: press 3-V.A.G 1552-: press ↑.
  
Read measurement value block    32    ->
                   1                   2
The display reads: (1...2 = display fields)
–  Watch the lambda regulation in display field 1. The value should oscillate 2 % minimum within the range: -10.0...10.0 %
–  Press →.
–  Press 0 and 6 for the function “End data transmission” and press Q to confirm the entry.
–  Switch off the ignition.
If lambda regulation does not oscillate in display field 1:
–  Test the lambda probe 1 wiring → .
If lambda regulation in field 1 does not oscillate within the indicated range:
–  Run a road test to clean the lambda probe of soot and repeat the test.
Take the necessary precautions during road tests → Chapter.
If the target value is not reached in display field 1 even after the road test or if the value does not oscillate 2 % minimum:
–  Check the pre-catalyst lambda probe ageing → Chapter.
Test the lambda probe 1 wiring
  
Read measurement value block    33    ->
                   1                   2
–  Connect test box -V.A.G 1598/22- to the control unit wiring harness.
  N24-0709
–  Unplug the 6-pin connector (black) to the pre-catalyst lambda probe -G39--arrow-.
  E24-0028
–  Test for open circuits in the wiring between the test box and the 6-pin connector (connector to the control unit) following the wiring diagram.
   Contact 1+female contact 46
   Contact 2+female contact 34
   Contact 5+female contact 20
   Contact 6+female contact 35
Wiring resistance: 1.5 Ω∼max
–  Test all wiring for short circuits between wires. Target value: ∞ Ω
If no fault is found in the wiring:
–  Replace the pre-catalyst lambda probe -G39- → Item.
  M24-0056

Post catalyst lambda probe and regulation: testing > < Idling test