I got the air cleaner off, and checked the current running through the EHA. I did get current running through the unit, but not 20 mA - on the 500 mA scale my multi-meter needle was pegged. (No idea on that one, I'm going to try again as soon as I can get my hands on another meter) I also checked the diagnostic socket; I don't have a digital multimeter so I can't configure it to read the lambda output, but I gathered from another post that it's some form of DC V, and I read zero volts out of pin #3. I took a look at the OVP relay while I was at it, other than a dent in the side (??) it looks fine, fuse is good.
Any clues on this one?