[radiorental]

"There are all kinds of reasons why a car has to behave differently while on a dynamometer and there are all kinds of special code branches that are executed only during test. For the programmers it probably was just another special case among many."

I think the point is that someone deliberately did this and they had their hands in the code. Yes, there are variants of the tune-able parameters for various regions and tests. As part of design and validation these can be used interchangeable on the test beds. However, someone, somewhere wrote the emissions defeator.

[sebastianavina]

remember, someone wrote the emissions defeatos, AND maintained the code for seven years until now.

[mpclark]

It may not have been actual code. Perhaps only values in a look-up table? Perhaps even values in an area of a multi-dimensional array that was never expected to be used.

[radiorental]

The tune-able parameters are lookup tables. I know that Ford, for example, will go through up to 15 iterations per day with testers in the field, in various physical environment, leading up to a release.

The code that detected whether the vehicle was on the road or being tested is what is at issue here. It was a software engineer/manager that implemented it.