Peugeot 607 auto gearbox issues

I also drive a Peugeot 607. Could it be the neutral position safety switch? When that goes bad, it can cause starting issues and weird transmission behavior. Does the error code mention anything specific?

Neutral position switch, huh? I'll check that. But would that also cause it to shift poorly and throw a code? Maybe I'm just screwed?

Indeed, a faulty switch might explain the starting problem, but given the additional symptoms you describe (slipping, error code), it points to a more complex issue with the transmission's control system, I am afraid. I would suggest taking it to a qualified workshop for proper diagnosis and repair.

Thanks a bunch for the heads-up. Turns out it was the control unit, like I feared. Cost me a grand to fix, but at least it's running smooth now!