SM5 Automatic Transmission Fault

Sounds like a gremlin in your SM5's gearbox. Engine not starting, check engine light, shifting issues, and stored error codes point to something more than a simple fuse. It's like faulty wiring; one problem triggers a cascade. Does the error memory specify any sensor or module? It may be a faulty transmission sensor giving the control unit bad data. Have you checked the gear linkage or shift lock mechanism for mechanical issues, like play or binding?

Thanks. I haven't checked those items yet but I appreciate the suggestion. Regarding the error memory, is it likely the control unit itself is defective? Is there any chance this is a simple fix, or am I looking at a costly repair?

Hard to say for certain without more detailed diagnostics, but all signs indicate a potential control unit issue. It's like a computer with a corrupted operating system; seemingly unrelated things start going wrong. I'd recommend taking it to a reputable workshop with the diagnostic tools necessary to pinpoint the problem. I hope it is a sensor. Control unit replacements tend to be on the upper end of the pricing scale. With the symptoms you describe, it’s likely going to require professional attention. This may cost around 1000€.

I appreciate the advice. I feared as much, but it's helpful to have a more informed perspective before taking it in. I will take it to a local service center and anticipate a repair bill of around 1000€. Thank you again.