Anyone even remotely interested in this has to go through Adrian Colyer's excellent review. If I am not wrong, there's even a book out there on this great emission detection workaround.<p><a href="https://blog.acolyer.org/2017/06/20/how-they-did-it-an-analysis-of-emissions-defeat-devices-in-modern-automobiles/" rel="nofollow">https://blog.acolyer.org/2017/06/20/how-they-did-it-an-analy...</a>