I just got the P0037 code and it comes on every 2nd or so startup. Besides the CEL the car is running really strong. How soon should I have this looked at? Just in a region where the nearest Mazda dealer is a few hours drive away.

I know it is the rear O2 sensor.

 

I just got this 15 min ago too along with two P0302 misfire codes (although I never got a flashing CEL). Any help is appreciated here.

I'm out of the bumper to bumper warranty. A few days ago I noticed my exhaust was a little rotten eggish as well but my OEM cat is less than 4K miles old. Grrrr.

 

I have looked at all the threads on this rear O2 sensor. Where is it located on the car? I have the same code; already checked it with code reader. Car runs great, but that CEL is driving me crazy. Dealer wants 400 plus 100 diagnostic fee to fix it.
Tell me where the thing is and I'll change it myself (I can order from Mazdarix or one of the others here). I have the diagnostic printout someone posted here. Looks easy.
Paul