2002 Chevy Avalanche CHECK ENGINE LIGHT

CHECK ENGINE LIGHT CAME ON, TOOK IT TO REPAIR SHOP, NEEDED 2 SENSORS AND CATALYTIC CONVERTER REPAIRED, THEY CHANGED OUT SENSORS, BUT I COULD NOT AFFORD THE CATALYTIC CONVERTER, WILL TAKE IT BACK, WELL SINCE THEN MY SERVICE ENGINE LIGHT DOES NOT COME ON AT ALL WHEN I TURN ON MY VEHICLE, DO YOU THINK THE LIGHT WAS DISC, AND IF SO HOW COULD I CHECK???