A 4.3l engine requires three steps before replacing the Catalytic Converter including raising and supporting the vehicle followed by skid plate and transmission crossmember removal. The right front connector position assurance (CPA) retainer needs removal before disconnecting the right front heated
Oxygen Sensor (HO2S) electrical connector from the engine wiring harness. Initial steps require disconnecting the right rear cpb retainer then removing the engine wiring harness electrical connector from right rear ho2s electrical connector before extracting the right rear ho2s clip from the engine harness clip. Continue this procedure for the left rear and left front ho2s connectors by removing both cpa retainers and their associated clips. First disconnect all required sensors before you remove the nuts from the Catalytic Converter to
Muffler interface and the Catalytic Converter to
Exhaust Manifold interface. Finally, separate the Catalytic Converter assembly from the exhaust manifolds and Muffler. When you plan to replace the entire Catalytic Converter assembly make sure to remove the exhaust seals along with sensors from the assembly. Before you install the ho2s to the Catalytic Converter assembly, treat the ho2s threads with anti-seize compound gm p/n 12377953 then tighten everything to 42 n.m (31 lb ft). A new exhaust seal installation may be necessary before you fasten the Catalytic Converter assembly to Muffler and exhaust manifolds by torquing nuts to 50 n.m (37 lb ft) and 45 n.m (33 lb ft). When installing the left front ho2s on 4wd vehicles connect the engine wiring harness electrical connector to the operating sensor then install the retainer clamp before fastening the ho2s connector. The right side sensor connection process continues while the transmission crossmember is installed with the oil pan skid plate positioned correctly before tightening its bolts to 28 n.m (21 lb ft). Once completed, lower the vehicle.