How to access the Engineering Mode
The first thing to note is that the Engineering Mode view, provided by HiddenMenu.apk, relies on specific modifications LG added to the framework, more specifically the sending and receiving of RIL_OEM_HOOK_RAW.
Hence, contrary to the SamsungServiceMode.apk that can be install on CyanogenMod, here HiddemMenu will not work on a CyanogenMod ROM without re-implementing the functionnality LG added to the phone class.
First, to get into the application, enter 3845#*802# (that's for the international LG G2 version). Then select "WCDMA-Only", then "Modem Settings", then "Engineering Mode".
Away for a short while