737NG DEU Failure
Basically, in a plain english explanation, if the EEC's fail to get their info from the right places, eg Adiru's which go through the DEU's, than, the EEC's have a redundant feature in them that makes them revert to a mode whereby they use their own information. Example is the static pressure port that it will use if the ADIRU's fail to supply ambient pressure etc. this is a soft fault.