Toyota 17141-16090 Exhaust Manifold

Disconnect the cable from the negative terminal of the battery, then raise the vehicle and support it securely on jackstands. Remove the three exhaust manifold-to-exhaust pipe nuts, followed by the two bolts from the center hanger exhaust pipe brace. Slide the entire exhaust pipe assembly to the left to disconnect the two rear braces from the rear hangers and remove it from the vehicle. From underneath the engine compartment, remove the three lower exhaust manifold insulator retaining bolts. Lower the vehicle and disconnect the oxygen sensor electrical connector. Remove the distributor cap, rotor, and shield, then take out the bolt that retains the throttle cable bracket and the engine compartment temperature sensor bracket, setting both brackets and their respective components aside. Remove the remaining three retaining bolts from the insulator and take the insulator off the exhaust manifold. Remove the EGR pipe bolt and the EGR pipe assembly, then take out the three bolts and two nuts from the exhaust manifold to detach it from the cylinder head. Scrape all old gasket material from the mating surfaces of the exhaust manifold and the cylinder head, and consider measuring these two mating surfaces for flatness before reinstalling the manifold. Installation is the reverse of removal, ensuring to tighten the exhaust manifold bolts to the specified torque.

The purpose of a catalytic converter is to reduce hydrocarbon, carbon monoxide, and nitrous oxide emissions by oxidizing and reducing these chemicals, converting them into harmless nitrogen, carbon dioxide, and water.