Hi Guys I Have a big problem, Please I need help. I have a 99 silverado I installed a 6.0 engine and a computer to match and a blower and a 4l60e trans also 410 gears I also have headers and gibson exhaust. my cats are original. know every once and a wile my check engine light will go on and its a catalytic converters problem light, now the shop took off the cats and inspected the cats and found no problem. now the shop says that if they replaced the cats that might not fix the problem. here is what they say I don't use the car enough and the cats have to get to 1400 degrees to clean them self out and I am not geting the car to that temp by not using it enough that is why my car is setting the check engine light to go on. Please tell me what you think. I don't think so.

 

rear O2 sensors?