check engine diagnosis

Yes, it is possible. There are generic OBD codes and specific manufacturer codes - which most generic scanner will fail to identify. It usually sees it as a " Unidentified or Undocumented Code". i.e.: on Volvos I have seen many falsely diagnosed codes by generic scanners. The other shop without the OE diagnostic computer kept receiving O2 sensor codes, they where repeatedly changing the O2 sensors, while the real problem where Mass Air Flow and Electronic Throttle Module problems, which did not appear on their scanner. Nothing beats the OE diagnostics. Cheap code readers or non-OE diagnostics could mislead you and you can keep spending money on unnecessary parts, meanwhile the real problem will remains. Zee