Waterproof, seperable, high temperature rated connectors MIL Spec. Splice Type Seperable wire splice. Lambda sensors etc. Connecting wire insulation will limit maximum temperature, silicone or PTFE insulated wire is needed above 100°C.
eBay
Image is Representational - See Manufacturer Specs | Automotive Connector JUNCTION Assembly - Position Circular - WIRE SPLICE - Connector - Size 20 - 1.109 Length The TE Connectivity / Deutsch TSE-20-01 is a JUNCTION Assembly/Position Circular/WIRE SPLICE Connector Size 20 used in Automotive applications .
eBay