Aged or failed bank 2 catalytic converter from normal thermal degradation; A lazy or contaminated downstream oxygen sensor on bank 2; Exhaust leaks ahead of or at the converter that skew the sensor readings; Engine misfires or rich running that overheated and damaged the converter; Oil or coolant consumption contaminating the catalyst substrate; A failing upstream oxygen sensor on bank 2 causing incorrect fuel trim; Restricted exhaust flow from a collapsed or melted substrate

DTC codes / P04xx · Auxiliary emission controls / P0432

P0432Main Catalyst Efficiency Below Threshold (Bank 2)

Q: What does code P0432 mean?

Main Catalyst Efficiency Below Threshold (Bank 2). P0432 means the powertrain control module has judged that the bank 2 catalytic converter is no longer cleaning the exhaust effectively. The computer compares the upstream and downstream oxygen sensor signals on that bank and flags the code when the downstream sensor tracks the upstream sensor too closely, indicating the converter has lost its oxygen-storage capacity.

P0432 means the powertrain control module has judged that the bank 2 catalytic converter is no longer cleaning the exhaust effectively. The computer compares the upstream and downstream oxygen sensor signals on that bank and flags the code when the downstream sensor tracks the upstream sensor too closely, indicating the converter has lost its oxygen-storage capacity.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaAuxiliary emission controls

Symptoms you may notice

Illuminated check engine light, often with no other symptoms at all
A slight drop in fuel economy as the engine runs richer in response
Failed emissions or state inspection testing
Occasional rough running or hesitation under light load
A faint sulfur or rotten-egg smell from the exhaust in some cases
Reduced power on grades when the converter is partially restricted

Common causes, most likely first

Aged or failed bank 2 catalytic converter from normal thermal degradation
A lazy or contaminated downstream oxygen sensor on bank 2
Exhaust leaks ahead of or at the converter that skew the sensor readings
Engine misfires or rich running that overheated and damaged the converter
Oil or coolant consumption contaminating the catalyst substrate
A failing upstream oxygen sensor on bank 2 causing incorrect fuel trim
Restricted exhaust flow from a collapsed or melted substrate

How to diagnose and fix it

Scan all stored and pending codes and check freeze-frame data to confirm the fault conditions
Inspect the bank 2 exhaust system for leaks, loose flanges and cracked pipes
Graph the upstream and downstream oxygen sensor signals on bank 2 to verify converter efficiency
Check fuel trims and misfire counters to rule out rich running or ignition faults damaging the converter
Test the downstream oxygen sensor response and replace it if sluggish or contaminated
Repair any misfire, fuel or oil-consumption issue before installing a new converter
Replace the bank 2 catalytic converter and clear codes, then complete a drive cycle to verify

Before you replace the catalytic converter

A downstream oxygen sensor that has gone lazy can mimic a dead converter, so always graph both sensors before condemning the catalyst.
An exhaust leak just ahead of the converter lets outside air in and makes a healthy converter look inefficient to the computer.
Unresolved misfires or rich fuel trims will destroy a new converter quickly, so fix the root cause first or the code returns.
On V-configured engines, bank 2 is the side opposite cylinder one, and technicians sometimes replace the wrong converter.
The code can set intermittently at steady highway speed even when the converter still passes a tailpipe emissions test.

Can I keep driving with P0432?

The vehicle is generally safe to drive with P0432 because it does not affect engine control safety, but avoid prolonged driving with a flashing check engine light or any misfire. Address it promptly to protect the converter and pass emissions testing.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.