Test Instruments DSO
The visible deviations (peaks) are not faults in the lambda probe signal, they are interferences from the ignition system. They are "received" via the adapter leads and the DSO lead.
The voltage signal for a rich mixture with little residual oxygen is approx. 0.7 ... 1.1 V. The voltage signal for a lean mixture with a lot of residual oxygen is approx. 0.1 ... 0.3 V.
The transition from rich to lean and vice versa is accompanied by a voltage jump from 0.7 ... 1.1 V to 0.1 ... 0.3 V or vice versa.
The control continuously oscillates between the statuses "slightly too lean" and "slightly too rich".
The following faults may be present if the change in voltage does not take place or is sluggish:
Holes in probe head blocked
Excessive thermal stress
Probe too cold, probe heating not functioning
Lambda control switched off, engine control unit has recognized fault in injection system -> interrogate fault memory.