Rotax really screwed up when they installed those Deutsch DT series connectors on the 912iS and 915iS. They're rated for 13A per contact, and they run right at the limit. I have no idea why they made the SI optional for the 912iS.
The Rotax-specified connector set (an Amphenol "ecomate RM") is about $460 from a Rotax dealer (see item 32,
here). You can buy the exact same connector parts from Mouser for about $71,
here. Tooling for these connectors' contacts is not cheap; see
here and
here -or-
here and
here.
If that's an Experimental aircraft and you want to do the repair at lower cost, consider using Amphenol ATP connectors instead. They're an exact copy of the Deutsch DTP (big brother to the DT that Rotax used) at barely more than half the cost. They can carry 25A per contact; more than enough for this application. A good quality crimper is
cheap. Amphenol ATP parts for this repair are
here. The genuine Amphenol crimper is the last item on that list (hint: it's the same tool with blue handles).
P.S. If you want tooling for all three sizes of connector (Deutsch DTM, DT, DTP / Amphenol ATM, AT, ATP), here you go:
DTM / ATM:
Amphenol AUTK-20 -or-
iCrimp IWD-20
DT / AT:
Amphenol AUTK-16 -or-
iCrimp IWD-16
DTP / ATP:
Amphenol AUTK-12 -or-
iCrimp IWD-12