Increased Emissions Warning and Check Engine Lamp are considered 2 things on a BMW.

A fault desription that shows the conditions of setting the fault will show how the Driver will be informed of the problem, either Check Control, or in conjunction with the CEL.

These so called fault descriptions are not always 100% true.

Ard, are you some kind of BMW technican? Ive seen many cars come in with CEL illuminated with no faults stored, EGS/SMG, and DME/DDE. Are you saying there could never be a problem with the instrument cluster, K-CAN/D-CAN network, or even a software error in the control units that illuminate the CEL without faults set?

Additionally not all faults are showed via "BMW Diagnostics" The majority of erronous faults are "masked" and hidden away from diagnosis to prevent mis-diagnosis. Some are shown in shadow memory, some are only available to engineers when sending FASTA data. Sometimes the car is too new to diagnose and we must wait for the lastest Diagnosis software.

So Ard, you do a disservice telling people "A CEL is set by a code, period. You cannot have a CEL come on without AT LEAST ONE underlying code."