Utkan Şenyüz, of the Master of None YouTube channel, had a leak in his evaporative emission control system (EVAP) on his car. You can buy a leak detector for around $50 and up (there are also canned smoke options), but Utkan wanted to roll his own. He explains:
I got a Engine Check light on my 2003 Toyota Matrix, code P0440 (meaning “Evaporative Emission Control System Malfunction”). That means I have a small leak in my EVAP system. The easiest way to find this leak is usually to use a smoke machine and look for the smoke. As usual, I wanted to make one myself. After looking around on the web, I got a paint can, clear tubing, and a couple of connectors. I did not want to pay for Vape system wire, so I used some stainless hanging wire I had laying around. I did not get the smoke coming out of the problem area on my gas tank on the video, but it turned out to be a return from evap system to tank that rusted out and broke off. I did not want to replace my tank so I used gas tank epoxy to repair the area.
After making the first paint can-based detector, Utkan was not entirely happy with the build, so he made a second one, out of a glass jar, for future troubleshooting. Give how rusted out the underbody of his ’03 Matrix is, I think he’ll have a future use for it.