[JFP in PA]

I would expect most “CEL” events to be non proprietary in nature. Because you are getting a “read error”, it may not be making the connection at the under dash port, a problem with the unit itself, or there may be a genuine inability for the DME to communicate. I would suggest trying another unit if you cannot get yours to function; if the second unit also cannot communicate, then there is an issue requiring some additional diagnostics……….