Mike, the car has no diagnostic capability as you guys in the US have. i.e. check engine light or pulse coding, but it has the control module (ECU) which has all the sensors connected (eng. & air temp, air mass flow meter, throttle switch, O2 sensor etc. and does the warm-up fuel enrichment, lambda closed loop control, WOT fuel enrichment, decel cut-off etc. I can only read the fixed duty cycle percentages (indicating different error conditions) on the X11 (pin 3) diagnostic socket.
Maybe someone else can help clarify this better?
1990 300E 320000 km