Not a stupid question. Yes you can, but it takes equipment I don't have. My rule of thumb is change it every 50K. And while you are at it, the crank position sensor and cam position sensor every 100K. Those two will leave you stranded when they quit. Basically what happens is that the O2 sensor generates its own electrical current. Eventually it starts running out of electrons it can get rid of so it starts generating less current and causes the engine computer to assume the mixture is lean and so it squirts more fuel into the cylinders. Short story is that they wear out just like solar panels