Oxygen sensor codes are set in the Engine Computer. There are dozens of them and they mean very different and specific things. Don't waste your money on an unneeded oxygen sensor. That will just lead to disappointment when the green light is still on. Check Engine lights are always red or yellow.
Being a green light you're seeing, that implies it is related to something not serious. The only thing I can think of goes back to the late '80s and early '90s when some cars had a "shift" light on the dash. Those were only used with manual transmissions. People thought they would get the best fuel mileage if they up-shifted when the light flashed on. In fact, the light did turn off each time you up-shifted, but that wasn't it's purpose. The actual purpose of those lights was for emissions testing. If you drove the car normally without paying any attention to that light, there could potentially be brief moments when emissions jumped too high. Rather than using common sense, that was enough for the politicians to have a hissy-fit and require pounds of solution for an ounce of trouble. Instead, the engineers put that "up-shift" light on the dash to tell the inspectors how to drive the car for testing. If they up-shifted the instant the light turned on, which was a little too early for comfortable driving, it would pass the emissions tests. This is a classic example of where the politicians, who know nothing about cars, were satisfied, and their goals were achieved, but a momentary glitch could wipe out common sense.
This didn't apply to cars with automatic transmissions, and it never stayed on steady, so I'm back to researching what your light is for.
Thursday, March 16th, 2017 AT 5:00 PM