Check engine set twice with code for ews input on peake reader car drives perfectly, no other codes reset and set CE light immed when started with same key; reset again and used other key, drove 200mi with no return of check engine light or driving issues. Aside from the obvious of not using the suspect key any thoughts as to why this would suddenly happen? 1998 Z3 5sp 80K miles--I do believe when this first happened battery charge may have been on low side from car sitting few weeks without using tender--could this possibly alter something on key chip?
If you have swapped keys and the fault did not return then I would say the key is causing the issue. Recommend getting a replacement key. I doubt the battery caused this light. But to confirm this just recharge the battery and use the key again that caused the CEL to come on. If it does the key is causing the issue if not then I would just drive it.
Ok at this point both keys set CEL and same code #94 EWS input. It seems that passenger door lock no longer opens automatically when driver side lock opened (trunk lock does open) and passenger side lock works only that door--could cause this code set for ews?
What engine do you have? Also what scan tool are you using? Code 94 has different means according to what DME and engine variant you have.
I wonder if you don't have a bad translation on the code reader for fault 94 from what I can tell 94 code for your DME is Tank leakage system large leak. Here is a quick list of faults according to DME. https://www.bmwcca.org/forum/index.php?threads/looking-for-a-repair-shop-start-here.10432/
