2002 WS6 is stock except for empty cats, I have had o2 sims from Afterthoughts in place for about four years and now I am getting ses light for both bank 1 & 2, po138 & po158.
Thinking maybe my sims had reached the end of their life span I replaced both of them again with the same Afterthoughts sims.
Logic tells me that both sims probably didn't fail at the same time but now even with the new replacements I get ses light with both codes, I have reset twice and now they are on again after only a couple days.

 

Those codes are for the front 02s. Going pig rich.
Temp gauge working right? Sensors could be shorted to voltage (melted at headers?)
MAF went ape ****?

 

No that's not right the code is Bank 1 Sensor 2 and Bank 2 Sensor 2 that is not the front o2 sensors, it is the ones post cats

 

O2 sims seem to be hit or miss whether they work or not. My dad put them in his old '03 Mach 1 when we put an off road X-pipe on it and they didn't work for ****. The only sure fire way to get around the codes is to get them tuned out.

 

You can't even buy sims anymore. They are illegal to sell. I would just do the above and get a tune and they can for sure turn them off. You will have to drive around afterwords for about 40-50 miles to clear it out even if the light is off cause it will screw you on an inspection if there are any recent failures still present.