Does the reader not have to be specific to a particular car type/engine or will any one do?
OBD II readers are, as you suggest, a bit hit and miss - so yes, they need to be specific.
I had to buy 3 before I found one that would work with my +8. One of the rejected models worked with Jenks's 8, but didn't work on mine.
Amazon is your friend here - you can return ones that don't work.
