cap'n, While I am no expert. I believe that if the system is open the EHA will sit at 0mA and not fluctuate. When closed the current will vary whether it needs a rich or lean mixture depending on the requirements of the cis brain (ECU). Now measureing it I can not help you I am afraid, have to pass you to steve.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)