Vito Dualiner 116 CDI SRS light Seat Belt Sensor

[Lomanator]

Hey guys, so I have the SRS light come on my dashboard on my Vito Dualiner 116 CDI.
Its the driver side seat belt sensor I'm pretty sure as it started to be intermittent.
Whats the best way to start the troubleshoot?
Mercedes replaced the seat belt buckle, says on the receipt, (MA639 860 00 69/ 9051 Fastener) which I believe is the part number. which was about 18 months ago and its gone wrong again.
Its is a simple enough thing to replace myself if needed?
Thanks for any help in advance

 

[m80]

Maybe later Vito's have seat belt sensing, early one's didn't.
It may well be the passenger seat occupancy sensor, has it been abused in any way?

 

[Lomanator]

Not abused but its does get used everyday maybe its just wear and tear, I'll take it apart and see what happens

 

[m80]

You would expect MB to read codes and get it right.
The issue herre is the cost of getting codes read might be greater than the repair.

I fitted Volvo seats recently and had to bypass the occupancy sensor of the passenger seat, the drivers seat doesn't have one. The kit comes with a seat belt bypass also which could be useful in your case should the 116 have this, even if just for diagnostics.
For Mercedes Viano Vito W639 Bypass Seat Occupancy Sensor Mat Emulator | eBay
That assumes the alarm doesn't latch and require a Star style reset, mine didn't.