I have found listings for Ox Sensors that say will fit the Vanagon for 1-wire, 2-wire, 3-wire, and 4-wire sensors. I pretty much have the 1 and 3-wire units figured out, but the questions are about the 2 and 4 wire options.

  Is the 2-wire internally grounded, or is that second wire an external ground? And would that be a good choice for Vanagons, given our constant ground issues?

  And I suppose the 4-wire is a heated, externally grounded unit, then, huh?

  Enquiring minds want to know...