both O2 rear sensors on my 05 Tacoma (V-6 4.0L) are giving codes P0037 & P0057. this is the 3rd time in less than 2 years. is the there something that could be causing this failure?

The set I purchased at Carquest (Denso brand), and the second set was installed at the Toyota dealer with OEM sensors.

Well Denso makes Toyota parts.. Go to autocodes.com and enter your code number.. Read the possibilities.. Without the vehicle present for hands-on scan testing, any advice anyone gives is just a best guess.. You may find some helpful information on that site.. Also look for any TSB's that may have been issued to address this problem.. Good luck with it!

Thank you