Join Date: Apr 2010
Ferrari Life Posts: 2,191
Traditionally, the SDL is triggered by too hot exhaust temperatures in the catalytic converters, measured by thermocouples at the exit of the cats. I've always believed O2 sensors had nothing to do with SDL's.
Recently however, some owners have reported that they've experienced SDL's and they've replaced things like their main batteries, the O2 sensors, RPM sensors, TDC sensors, etc. and the SDL's have disappeared afterward. Personally I don't buy it, but.......
I've done a fair amount of R&D work on these SDL systems as I had developed an in-cabin instrument to show actual temps AND trigger the SDL's when appropriate, so I'd like to know more about your current issues.
Is your 456 an early model or an M car? Reason I ask is to know which version of the Motronic ECU's you have. I'd also like to know if you still have the cat thermocouples and their ECU's in the system or not?
'99 550, Rosso Corsa / Nero, S/N:114654, Assy: 31836, Engine: 52084
High mileage, low compression, and missing on a few cylinders.....just like my cars.
Maranello Skunkworks Team Member