Technical Service Bulletin Oxygen System Check

Subject: Oxygen Sensor System Check   Models: 911/924/924 Turbo ALL

Bulletin Number: 80 – 02

When diagnosing poor engine operation, first perform a quick-check of the Oxygen Sensor System

Work procedure:

                Preliminary Conditions

  • Engine in proper tune (ignition timing, idle speed etc.)
  • No exhaust leaks
  • Engine at operating temperature
  • Connect Siemens 451 tester as follows:
  • “+” lead to battery terminal or equivalent
  • “-“ lead to OXS test connection No. II (marked on the back of plug)
  • “%” button on test instrument pressed in
  • Tester set for four cylinders


When making OXS test, do not connect any other test leads. Ignore figures in “RPM” window.

  • Note readings as follows:

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