1999 Corvette P0137 + P0157 - failed emissions test

My girlfriend just took her 99 Vette in for emissions testing and it failed with P0137/P0157 - O2 sensor low voltage bank1/2 codes. The car has about 80,000 miles on it. Bone stock except for Borla cat-back exhaust which was installed when the car was new. No drivability issues - car runs and performs fine. Having read the posts, it seems most likely that the downstream O2 sensors have gone south. Is this correct? Hate to spend $200+ if that's not a good starting point. I can clear the codes but have no special scan tools and don't want to get taken to the cleaners by the dealer. Would appreciate feedback on the most appropriate steps to take. Thanks, Ed

Want to clear the codes? Go to Auto Zone. The employees will not do it for you but they will hand over the scanner for you to delete them. Auto Zone will check your codes for free.

Check for bad connection first. Like loose, corroded, dirty, anything obvious that might hinder the electrical connection. If all checks out the O2 could be bad. I know, those puppies are expensive !!!