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

Note

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

Note readings as follows:

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