My 98 SS (@ 90k miles) has recently begun throwing codes 131 and 151. 131 throwing @ 1 time a week and 151 a few times (seems related to accelerating hard?).

Does this mean both O2 sensors are bad or is something else wrong that is causing both codes to light up?

New plugs and wires @ 4k ago.

What are trouble-shooting steps?

Thanks guys

 

At 90k, they are probably on their way out...especially if you've used any high octane gas at one time or another. Even certain additives can negatively affect them.