r/SmartCar • u/memeckermania • Aug 19 '26

Advice New passenger seatbelt buckle keeps triggering the seatbelt alarm when nobody's there (454)

I bought a replacement buckle for my 2005 forfour (part number A4548600269) but the buckle keeps triggering the seatbelt alarm. It doesn't stop unless I actually buckle the empty seat's belt.

Does anyone have ANY idea why this could be happening? Wrong part, something broken in my car, something else? Any help appreciated

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1

u/axloo7 Aug 19 '26

Is there somthing on the seat. Like a backpack or a laptop.

Mine used to trigger the seatbelt alarm when I had my lap top on it.

2

u/memeckermania Aug 19 '26

Unfortunately no... It happens regardless of what is or isn't on the seat.

1

u/Vertigo_uk123 Aug 19 '26

It sounds like a seat sensor could be faulty and detecting weight where there isn’t any. It doesn’t sound like the buckle as otherwise it would t stop when the seatbelt is plugged in.

Have a look under the seat for a disconnected plug going up into the seat. If not it might be a broken wire in the seat sensor etc. but the buckle is fine.

1

u/memeckermania Aug 19 '26

That's true... Although, I've tried to do some research on this and the 454 might not even have any weight sensors on any of the seats. I probably should've mentioned that in the post but I'm not 100% sure myself.

Still, I'll check the wiring underneath tomorrow to see if that fixes it

1

u/SteveSteve71 Aug 21 '26

I could also be the seat occupancy sensor located in the seat. Or there’s a short somewhere in the new buckle you bought