Lambda probe diagnosis method detects output signal of lambda probe during periodic variation in engine fuel/air ratio for providing diagnosis value

摘要

The diagnosis method detects the output signal (LAM) of the lambda probe (14) inserted in the exhaust gas line (12) of an IC engine (10) during a periodic variation in the fuel/air ratio supplied to the engine, for generation of a diagnosis value. The frequency of the periodic variation is altered until the lambda probe signal reaches a threshold value, at which the diagnosis value is obtained.