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Injectors: checking > < Coolant temperature sender: checking

Leon Mk2

Intake air temperature sender: checking
   
Intake air 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
t  Chilling spray (commercially available)

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 2 for “Display group number 2” 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)
–  Read intake air temperature value in display zone 4.
  
Read measured value block 2           ->
         1         2         3         4
IndicatedCauseContinuation of check
-40 °COpen circuit or short circuit to positive →  
129 °CShort circuit to earth →  
Approx. ambient temperature → Note— →  

1)  If a temperature is displayed which is below the ambient air temperature of the sender, check sender wiring for transfer resistances. Note that sender may be heated by radiated heat when engine is not running.
If the display indicates approx. -40 °C, continue checking as follows:
   
–  Pull connector -1- off the intake air temperature sender -G42- with intake manifold pressure sender -G71--2-.
–  Bridge connector contacts 1+2 with auxiliary cables from -V.A.G 1594 C- and observe display.
Indication of 129 °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 the intake air temperature sender -2- with intake manifold pressure sender -G42- → Item.
Display value approx. -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.
  N24-0307
–  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.
  N24-0305
ContactTest box -V.A.G 1598/18-, socket
243
Wire resistance: 1,5 Ω max.

–  Also check wiring for short circuits 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
If the display indicates approx. 129 °C, continue checking as follows:
   
–  Pull connector -1- off the intake air temperature sender -G42- with intake manifold pressure sender -G71--2-.
Display value approx. -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 the intake air temperature sender -2- with intake manifold pressure sender -G42- → Item.
–  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 wiring to the control unit connector at 4-pin connector, contact 2, for short circuits to wire contact 1 and vehicle earth.
   Specification: ∞ Ω
If no wiring fault is detected:
–  Renew engine control unit → Chapter
Continuation of check when display = ambient temperature:
  N24-0305
–  Remove intake air temperature sender together with intake manifold pressure sender (connector remains connected).
–  Note intake air temperature value in display field 4.
–  Spray sender with commercial chilling agent while observing the temperature value. The temperature value should fall.
–  Press the → key.
–  Press keys 0 and 6 for the “End output” function and confirm input with the Q key.
  N24-0320

Injectors: checking > < Coolant temperature sender: checking