GM 25817493
Catalytic Converter

Start by supporting and raising the vehicle then remove the heated Oxygen Sensor electrical connector. First position the jackstand under the Muffler before removing Exhaust Manifold to Catalytic Converter nuts followed by Catalytic Converter to Muffler nuts. Separate the converter from its hanger position before removing the Catalytic Converter. Support the converter installation phase to avoid damaging the flexible coupling while keeping the assembly's rear vertical movement limited to 6 degrees. Connect new gaskets to the Muffler studs as well as the Exhaust Manifold studs before putting the Catalytic Converter into position. Feed the converter to both the hanger and Muffler studs before executing a pulling motion to slide it into position on the Exhaust Manifold studs. Ensure the Catalytic Converter remains tight against Muffler nuts before you apply torque to Exhaust Manifold nuts with 35 n.m (26 lb ft) force then install 34 n.m (25 lb ft) torque on Catalytic Converter Muffler nuts. After removing the jackstand under the Muffler you should reconnect the ho2s electrical connector before lowering the vehicle.

Install the exhaust crossover pipe and secure it with the exhaust crossover pipe nuts, tightening them to 20 N.m (15 lb ft).

Disconnect the heater hoses from the heater pipes and remove the nuts securing the heater pipes to the throttle body, then position the heater pipes out of the way.