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Test lambda probe signal line and lambda probe control unit > < Check the function of the lambda control

Octavia Mk1

Check lambda probe heater
Check lambda probe heater
Special tools and workshop equipment required
t  Handheld multimeter, e.g. -V.A.G 1526 A -
t  Voltage tester, e.g. - V.A.G 1527-
t  Measuring tool set - V.A.G 1594 A-
t  Test box -V.A.G 1598/22-
Test conditions
l  The fuse no. 43 must be o.k.
Procedure
The heating circuit of the lambda probe is monitored by the self-diagnosis.
–  Interrogate the fault memory → Chapter.
–  Disconnect the 4-pin plug of the lambda probe (on the underside of the vehicle on right in direction of travel, below a cap).
   
–  Perform resistance measurement between the contacts 1 and 2 of the probe connector.
  Note
At ambient temperature the heating element resistance is of approx. 1 to 5°Ω. The resistance increases considerably even if the temperature rises only slightly.
–  Replace the lambda probe if an open circuit is detected.
If there is continuity in the heating element, check the power supply for lambda probe heater as follows:
  S24-0291
–  Connect the multimeter between contact 1 of the plug at the wiring loom and the engine mass.
–  Operate starter briefly (the engine can also start briefly)
Specified value: approx. battery voltage.
–  If the specified value is not reached, test the wiring of contact 1 of the plug at wiring loom for continuity and/or short circuit to earth, if necessary repair → Current flow diagrams and Fitting locations.
–  Connect the test box -V.A.G 1598/22 - to the wiring loom of the engine control unit → Chapter.
–  Test wiring of contact 2 of plug at wiring loom (earth control of the engine control unit) to contact 27 at engine control unit for continuity, if necessary eliminate line interruption.
–  If fuses and cables are o.k. but neverthless the specified value is not reached, test fuel pump relay → Chapter.
–  If all previous tests which were carried out are O.K, replace the engine control unit → Chapter.
  S24-0291

Test lambda probe signal line and lambda probe control unit > < Check the function of the lambda control