Audi Workshop Service and Repair Manuals

Note:

The lambda probe signal is monitored by the self-diagnosis system.

• ‒ Interrogate fault memory .

• ‒ If a fault in the lambda probe is displayed and the lambda probe heating is OK, unplug the lambda probe connector.
• ‒ → Test voltage by connecting hand-held multimeter V.A.G 1526 (measuring range 2 V) between sockets 3 and 4 of connector on wiring harness.
• ‒ Switch ignition on.

• Specification: 450 ± 50 mV.

If the specification is not attained:

• ‒ Test lambda probe wiring
  

If the specification is obtained:

• ‒ Renew the lambda probe.

Test lambda probe wiring

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
  => Page 24-10.
• ‒ → Test the following wiring connections for open circuits:

• Resistance in wiring: max. 1.5 ω

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ → Test wires on 4-pin connector for short circuits with each other.

• Specification: infinity ω(open circuit)

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ Test screening wire for short circuit to probe wiring.

• Specification: infinity ω(open circuit)

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

If no faults are found in the wiring:

• ‒ Fit a new engine control unit -J220
  => Page 24-13.