The code was supposedly written by a vendor or subcontractor, so it could have been delivered in a &quot;drop&quot; to VW without commit history.<p>Also, the story seems to have been that the &quot;cheat&quot; was a special mode explicitly programmed for test purposes and not something totally under the covers. The &quot;crime&quot; was in enabling that mode under field conditions. That change may not be covered by source code revision control, if it were made in a config file outside of SCC.<p>In a field more of us here understand, it would be similar to coding a feature in a server that dumps user passwords to the log file in plain text. Such a feature would be useful for certain debugging situations, but it would be disastrous to have it enabled on a production box. So you&#x27;d put a big all-caps warning in the source code, documentation, example config files saying whatever you do don&#x27;t turn this on in production. Supposedly the engine management developers did something along those lines, but the folks who built the cars ignored the warning and enabled the mode anyway.