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Test Point 8 - Oxygen Regulation Stop

TEST POINT 8 - Oxygen regulation stop - Fault code 1_23

Possible Causes, Elimination, Remarks
The oxygen regulator cannot operate within its control range if extreme problems of mixture preparation occur, e.g. due to an excessively lean setting because of unmetered air, or due to an excessively rich setting because of a faulty injector valve. The oxygen regulator then moves up to the stop position.

Oxygen regulation stop too rich:
Check intake system for leaks, Test Point 29 - Intake System Leaks

Oxygen regulation stop too lean:
Check fuel pressure, Test Point 28 - Fuel Pressure
Check injector valves for leaks