They should be covered no matter what. At 27,000 miles I would expect you would be under the factory warranty, but I also am 99% sure that O2 sensors are part of the emissions system and will be covered.
Also, you don't have to go to the dealer if you have a quality mechanic who can do this. I'm pretty sure that they can do GM warranty work as long as they know how. I know my mechanic told me so when I brought our Blazer to him after the warranty ran out. He told me that I could have been bringing it to him all along. Our O2 sensors are still going OK after 115K miles and almost nine years. Brad Waller ([EMAIL PROTECTED]) '66 Corvette | 327/dead | 4-speed | Wilwood Brakes | 245/45/16 BFG R1 '67 Chevelle | ex-SS396 | 355/700R4 | F-Body Brakes | 275/40/17 Kumho MX > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Malibu > Sent: Wednesday, April 11, 2007 3:03 AM > To: The Chevelle Mailing List > Subject: Re: [Chevelle-list] OT: Universal O2 sensors > > I thought these sensors were part of the emission control system and were > warranted for 100,000 miles. My "check engine" just came on in my Blazer > with 27,000 miles on it. I found 2 sites that talk about testing and > repairing. If their not warranted, I sure don't want to go to the dealer and > get ripped. I'll try and check it myself. > http://www.bobblick.com/techref/projects/o2sensor/o2sensor.html > > http://www.unofficialbmw.com/all/engine/all_o2sensor.html