P0432

What it means

P0432 means the engine control unit has judged that the main catalytic converter on bank 2 is not storing and converting exhaust gases as well as it should. It usually compares the signal from the upstream oxygen sensor with the downstream sensor on that bank. If the downstream sensor mirrors the upstream switching too closely, the catalyst is flagged as below its efficiency threshold. Bank 2 is the side of a V or flat engine that does not hold cylinder number one.

Symptoms

• Malfunction indicator lamp on
• Usually no change in how the car drives
• Possible smell of rotten eggs from the exhaust
• Slightly higher fuel consumption
• Failed emissions test at an MOT or inspection
• Reduced power if the catalyst is partly blocked

Possible causes

• Worn or degraded catalytic converter on bank 2 due to age or mileagelikely
• Catalyst damaged by misfires, rich running or contamination from oil or coolant burninglikely
• Faulty or slow downstream oxygen sensor on bank 2possible
• Exhaust leak before or near the oxygen sensors on bank 2possible
• Damaged wiring or connector to the bank 2 oxygen sensorspossible
• Fuel trim problem on bank 2 such as a vacuum leak or leaking injectorpossible
• Outdated engine control unit software where the manufacturer has issued a known update for catalyst monitoringrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting load, engine speed and temperature when the code set
2. Check for other codes, especially misfire, fuel trim or oxygen sensor codes, and deal with those first
3. Visually inspect the exhaust from manifold to catalyst for leaks, damage and loose joints, and check the oxygen sensor wiring and connectors
4. Check short and long term fuel trims on bank 2 for signs of a rich or lean condition
5. View live data of upstream and downstream oxygen sensors on bank 2 at a steady warm idle and 2500 rpm; a healthy downstream signal should be steadier than the upstream one
6. Check the downstream sensor response and heater operation, and compare with bank 1 on the same engine
7. Check for signs of oil or coolant consumption, such as white smoke, oily spark plugs or low coolant
8. Check for any manufacturer software updates relevant to this model and engine before replacing the catalyst

How to fix

• Repair any exhaust leaks found upstream of or near the oxygen sensors
• Repair damaged wiring or connectors to the bank 2 oxygen sensors
• Replace the downstream oxygen sensor on bank 2 if it is shown to be faulty
• Correct the underlying cause of misfires, rich running or oil or coolant consumption before fitting a new catalyst
• Replace the bank 2 catalytic converter with a suitable one once the cause of failure is dealt with
• Apply a manufacturer software update only if one is documented for this fault on the specific model

Can I keep driving?

Nearby codes

• P0431GenericCatalyst 1 Efficiency Below Threshold Bank 2
• P0433GenericHeated Catalyst Efficiency Below Threshold Bank 2