93 4cyc x-cab truck 186,000 miles . E-light comes on and stays on untill i disconnect battery cables to reset. I think o2 sensor any other common problems with 22re . i think original o2 sensor had tk since 80,000 only replaced head gasket timing chain, cam. truck runs great ! Have 15,000 miles on since repair. i guess i sould spend $80 on a new o2 sensor to pass emissions test, also might be burning alittle rich.