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Intake air temperature sender: checking > < Intake manifold pressure sender: checking

Leon Mk2

Coolant temperature sender: checking
   
Coolant temperature sender: checking
Special tools and workshop equipment required
t  Hand multimeter -V.A.G 1526 A- or multimeter -V.A.G 1715-
t  Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with cable -V.A.G 1551/3B-
t  Auxiliary measuring set -V.A.G 1594 C-
t  Test box -V.A.G 1598/18-
t  Current flow diagram

Test conditions
l  Engine cold
Checking process
–  Connect fault reader -V.A.G 1551- (-V.A.G 1552-). Start engine and enter “Address code” 01 to select engine control unit. (Fault reader: Connecting and selecting the engine control unit → Chapter.)
   
Indicated on the display:
–  Press keys 0 and 8 for the function “Read measured value block” and confirm entry with the Q key.
  
Rapid data transfer                 HELP
Select function XX
Indicated on the display:
–  Press keys 0, 0 and 1 for “Display group number 1” and confirm entry with the Q key.
  
Read measured value block           HELP
Input display group number XXX
Indicated on the display:
(1…4 = display zones)
–  Note coolant temperature value in display zone 2.
  
Read measured value block 1           ->
         1         2         3         4
IndicatedCauseContinuation of check
-40 °COpen circuit or short circuit to positive →  
128 °CShort circuit to earth →  
Approx. coolant temperature → Note—Only if sporadic faults have been detected: → Note → 

1)  If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check sender wiring for transfer resistances.
2)  Check is only possible when the engine is cold.
Continuation of checking in case of reading -40 °C:
   
–  Pull 4 pin connector -1- off coolant temperature sender -G62--2-.
–  Bridge connector contacts 1+3 with aux. cables from -V.A.G 1594 C- and observe display.
Indication of 128 °C:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Renew coolant temperature sender -2- → Item.
Indication of -40 °C:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
  E24-0146
–  Connect test box -V.A.G 1598/18- to control unit wiring harness.
  N24-0334
–  Check the wiring between test box and 4-pin connector for open circuit using current flow diagram.
  N24-0147
ContactTest box -V.A.G 1598/18-, socket
342
Wire resistance: 1,5 Ω max.

–  Check wiring additionally for short circuit to battery positive.
   Specification: ∞ Ω
–  Check the wiring between test box and 4-pin connector for open circuit using current flow diagram.
   
ContactTest box -V.A.G 1598/18-, socket
117
Wire resistance: 1,5 Ω max.

If no wiring fault is detected:
–  Renew engine control unit → Chapter
Continuation of checking in case of reading 128 °C:
   
–  Pull 4 pin connector -1- off coolant temperature sender -G62--2-.
Indication of -40 °C:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Renew coolant temperature sender -2- → Item.
Indication of 128 °C:
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
–  Switch ignition off.
–  Remove the connector of the engine control unit.
–  Check the wire between the control unit connector and the 4-pin connector, contact 3, for short circuits to wire contact 1 and vehicle earth, using current flow diagram.
   Specification: ∞ Ω
If no fault in wire is detected:
–  Renew engine control unit → Chapter
When the coolant temperature is displayed, continue check as follows:
Functional check of sender
–  With the engine running, observe coolant temperature value in display zone 2. The value must increase uniformly without interruption.
  Note!
t  If the display on fault reader jumps by 2…5 °C, it is a control unit fault and not caused by a defective sender.
t  If irregular engine running occurs within certain temperature ranges and the temperature figure does not increase without interruption, the temperature signal is temporarily interrupted and the sender must be renewed.
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
  N24-0147

Intake air temperature sender: checking > < Intake manifold pressure sender: checking