Bought a 99 suburban a few weeks back and the previous owner had it straight piped. So now my ses light is constantly on and I feel that my gas milage is suffering too. I was told I could get something called a shunt to trick the computer into thinking the O2 sensors are reading correctly, but I've had less than no luck. I've checked everywhere I can think of. Parts stores, jegs, summit, eBay and none of the kids nes I've found are compatible with my 5.7 vortec, their usually for a Honda or someotyer little car. I've also read the pcm will need to be tuned/reprogrammed, black bear performance is a name I keep hearing but spending $500 for a tuner isn't an option for me with the holidays coming up.

 

A shunt is a term for a resistor/jumper (electrical). O2 sensor is for emissions. I have an 02 Mazda that has no cat on it because of it being plugged.