My 09 Tacoma V6 Maintenance light has come on. I checked the oil, it was low so I added about a 1/2. The light is still on. I had the oil changed back in the summer. I have 32,000 mi on it & all maintenance done by a Toyota Authorized Dealer. Last oil change was back in the summer. Is there a sensor or something that perhaps didn't get reset? This light has never come on before, I don't drive the hell out of my truck. The 3yr service was done last Dec. the only thing not done was plug replacement. What is the reason for the light to come on?