I am afraid I still don't believe the story about sucking oxygen through the tightly insulated wires to the lambda sensor for an external reference oxygen level. There are plenty of posts and videos on the Internet from folks who soldered their lambda wires with no problems. However, I followed the Bosch instructions and used their compression connectors but I would guess that if an M3W were to use these connectors in a damp or salty environment, corrosion problems would occur. Luckily mine is only ever used in the warm and usually dry climate of the south of France in the summer. Sadly I cannot see my M3W getting any use at all this year with France having gone into another lockdown.
Wilson
