My vehicle had a check engine light (sometimes called Malfunction Indicator Light or MIL) come on. And after inspecting the fuel cap O-ring and fuel port rim, and all the vapor lines; the next step took me to a test of the fuel cap.

In this video https://youtu.be/veDvO-FUWO8 , I talk about the evaporative emission control system, the modern fuel cap, Pirani gauges, and the op amp-based circuit to run the Pirani gauge.

Each topic is covered quickly and I'm happy to engage with you more in the comments. I made this for the op amp challenge, and it's my first post on the site. Looking forward to more projects and challenges.