The plan was to fail warning lamps for safety related systems (airbag, esp etc). As has been said, the media will never let the truth get in the way of a good story, and included engine MILs too. However the likes of Peugeot with their 2 stage warning lights (passenger airbag deactivation puts the warning lamp on) caused confusion! Until they've logged all the different variations, the warning lamp fiasco, will remain an advisory only.

It makes me laugh, that engine mils were introduced in the early 00's for emissions reasons, and then nothing has been done to use them for the correct reasons.