P0432 Main Catalyst Efficiency Below Threshold (Bank 2)

P0432 indicates main catalyst efficiency below threshold on Bank 2. The controller believes the Bank 2 catalyst is not storing oxygen or converting exhaust effectively enough.

Code details

Generic OBD-II · P0

System: Emissions
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the Bank 2 catalyst until sensor data, exhaust sealing, fuel trims, and misfire history support that diagnosis.

Symptoms of P0432

Check-engine light, often with no obvious change in how the car drives.
A failed emissions test or incomplete readiness monitors.
Sometimes a faint fuel-vapour smell (on EVAP codes).

Common causes of P0432

A worn catalytic converter or an oxygen/air-fuel sensor reading out of range.
EVAP leaks — a loose or failed gas cap, cracked hose, or purge/vent valve.
Exhaust leaks, fuel-trim problems, or a fault in a related monitor.

Useful checks before replacing parts

Compare Bank 2 upstream and downstream oxygen sensor switching, catalyst monitor results, fuel trims, exhaust leaks, freeze-frame load, and catalyst temperature.
Inspect for Bank 2 misfires, rich or lean operation, oil or coolant contamination, exhaust leaks near sensors, damaged substrate, and sensor installation issues.
Verify engine operation and sensor accuracy before deciding the Bank 2 catalyst itself has failed.

Related OBD-II codes

These nearby emissions entries can help compare wording and pin down the fault area.