I recently asked that question of a Toyota service manager and was told that past the 3yr/36,000--oxygen sensors are only covered till 8/80,000 in California. I just replaced one on a 2002 4 cyl with 48,000. Denso part and my labor $93.

 

Thanks. I think that MA is same as CA regarding emissions warranty so I may be in luck. I will call the dealer today, but wanted to get others experiences before doing so.