Resetting 0-2 sensor warning

The dash warning light indicating you need to replace your oxygen sensor is merely a timed popup. It doesn't mean anything has happened functionally except that it has been x miles since the odometer-connected timer was reset.

To reset the meter, crawl under the Vanagon under the driver's seat and trace the speedometer cable to the point where it terminates into the little box mounted undernearth the floorboard. There, you'll find a reset button. I don't remember exactly, but I think you need a small object like a nail to accomplish the reset. But you'll hear a "clunk" when you succeed.

BTW, the most common problem I've found wtih O2 sensors is the wiring connector from the sensor (located in the exhaust pipe under the engine) to the engine's computer. Replacement after-market sensors don't come with a connector and must be spliced in. This splice can work itself loose.