What I have is closest to the firewall is a 2 prong sensor, next is a 1 prong sensor and then approx. midway on the intake is the 3 prong sensor. I'm guessing that the 2 prong feeds my engine temp indicator on the instrument cluster, the 1 prong ???, but my mercedes parts guy is more or less (3rd party info thru my wife) confirming that the 3 prong feeds my computer info, can anybody back this up?