Soldering is fine and heat shrink. Make sure to slide the heat shrink on the wire before soldering both ends.
I used some harness heat tube I bought from DEI for the extensions.
I used twisted pair wire on the signal wires as the harness is also using twisted wire.
Signal wires are those marked I/J on the schematic.
Wire gauges are listed as 0.5mm or 1.0mm. You can use the closest larger aproxímate AWG size.
Schematic
1vK means 1 vor Katalysator or before Catalyzer.
1nK means 1 nach Katalysator after Catalyzer.
