SM3 Alarm System Failure

Sounds like a real pain! I've seen similar things happen, and it's usually something simple but annoying to track down. Have you tried checking the fuses related to the alarm system? Also, where exactly is the error memory pointing? Knowing that could give you a clue as to which cable or plug is the culprit. Did you recently have any work done on the car? Sometimes these things pop up after messing with something else entirely.

Thanks for the reply! I did check the fuses, all seem fine. As for the error memory, it's just a general 'siren communication fault'. I haven't had any recent work done, which is weird. Any idea where the alarm controller is located on these SM3s?

Okay, 'siren communication fault' isn't super helpful, I agree. Honestly, tracing that down without the proper tools could be a headache. Given it's likely a wiring or connector issue, and you haven't had any recent work, I'd suggest taking it to a workshop. A proper diagnostic should pinpoint the problem quickly. I remember chasing a similar gremlin in an old Megane once, spent hours only to find a corroded connector. Cost me more time than it would have just to have a professional look at it. Expect around 95€ for the repair.

Appreciate the advice. I was hoping it would be a simple fix, but sounds like a workshop visit is the best option. Thanks!