Originally Posted by Rowe

how is the tester suppose to know the the EGR system is missing?
also, i'm not entirely convinced the EML is actually classed as a warning lamp:

If you've got one of these warning lights then it must now work correctly:
Electronic parking brake
Electronic stability control
Headlight main beam warning light
Electronic power steering warning light
Brake fluid level warning light
Seat belt pre-tensioner warning light