Main Catalyst Efficiency Below Threshold (Bank 2)

P0432 indicates the main (underbody) catalytic converter on Bank 2 is below efficiency threshold. On Ford trucks, this is the large converter under the passenger side. Before replacing, check for exhaust leaks at all flanges and ensure no misfire codes are present. Replace with a direct-fit Dorman or Walker converter. Must be CARB-compliant in California and section 177 states.

On GM trucks, the main underbody converter on Bank 2 degrades over time, especially with oil consumption from AFM (Active Fuel Management) lifter issues. Fix any oil consumption issues first -- Then replace the converter. Disable AFM with a tuner to prevent recurrence. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN.

The Nissan engine is generally reliable, but the Bank 2 main cat can fail at high mileage. Symptoms include a sulfur smell and reduced fuel economy. Verify by comparing front and rear O2 sensor waveforms on a scan tool -- if the rear sensor mirrors the front, the cat is dead. Replace with a direct-fit converter. Eastern Catalytic and Walker make direct-fit options. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.