I read somewhere else that you can't solder Lambda cables as the cables need to breathe, which sounds like total BS to me. Soldering does not change the resistance by much (fractions of an Ohm) especially if you use Mundorf silver/gold/tin solder with a thermostatically controlled iron, like I do. I would also bet that the soldered joint has over time, a far more constant resistance than the screwed together joint that Bosch supply, where the surface of both the connector slugs and the wires will oxidise and in damper, colder climates than where I am using my M3W, corrode
Carroll Smith, whose books I thoroughly recommend to anyone working on or building competition cars (Prepare to Win, Engineer to Win, Tune to Win), said that crimped or screw down terminal block joints were an absolute no-no on race cars as they would inevitably go high resistance or fail. I prepared my various single seat F2 and F3000 engined speed hill climb cars according to his principles and those of the late Ron Tauranac, always using ring-locked, surface-mount aircraft style connectors and as a result, during the 15 years I campaigned those cars, they never had an electrical failure (plenty of other failures - mainly gearboxes, which lead a hard life on hill climb cars).
Wilson
You cannot solder o2 cables, as the reference (static) oxygen has to flow between the wire core and the insulation around it (and/or between wire strands).
