VW Is Said to Cheat on Diesel Emissions;

[mrlynn]

So was this 'defeat' software designed to work automatically by detecting when an emissions test was being performed, or was it activated by a switch the owner could control? The article suggests the former, but I wonder how that would work.

Used to be emissions testing was done with a sensor up the tailpipe, but I gather that's been superseded in many places with some kind of computerized test--using built in sensors, or what?

/Mr Lynn