What is the difference between P0430 and P0432?

Both are Bank 2 catalyst efficiency codes. P0430 is the generic OBD-II code used by most manufacturers. P0432 is used by some manufacturers (commonly Chrysler-Jeep and some European brands) to specifically label the main catalyst when the exhaust has a separate warm-up pre-cat and main cat per bank. The diagnostic approach is essentially identical.

Can I replace just the Bank 2 main cat and leave Bank 1 alone?

Yes, if Bank 1 shows no efficiency codes and the downstream O2 sensor traces look healthy. On a high-mileage engine the Bank 1 cat has the same age and duty, so it is worth having it checked while the car is up; replacing both at once can save overlapping labour if Bank 1 is also near the end.

Why does only Bank 2 fail when both banks have the same mileage?

Asymmetric wear is common. Causes include intake manifold geometry that delivers a slightly different air-fuel ratio per bank, exhaust packaging that traps more heat on one side, or a single failing injector or coil that has been quietly causing partial misfires on Bank 2 for months.

Will an aftermarket Bank 2 main cat pass emissions?

A replacement main cat has to hold enough oxygen for the catalyst monitor to pass it. Choose one specified for your exact engine and carrying EU type approval (an E-mark), rather than a universal converter that is not matched to the engine, which may not pass the monitor and can set P0432 again.

P0432: Main Catalyst Efficiency Below Threshold (Bank 2)

Quick Answer

Safe to drive (short-term)

P0432 means the main catalytic converter on Bank 2 has dropped below the efficiency threshold the ECU expects. Bank 2 is the cylinder bank that does not contain cylinder 1, so P0432 only applies to engines with two banks, each with its own catalysts: V6, V8 and larger engines, boxer engines, and some inline-sixes that split their exhaust in two. It is the Bank 2 equivalent of P0422.

Severity: Moderate · Emissions
Estimated repair cost: From €125 to €1800+, varies by vehicle

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What does P0432 mean?

P0432 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0432 and illuminates the check engine light.

Where it is on the car

Engine
Oxygen sensor before the converter (sensor 1)
Catalytic converter
Oxygen sensor after the converter (sensor 2, or 3 on some cars)
Silencer and tailpipe

This code is for bank 2. V6, V8 and flat engines have two cylinder banks, each with its own converter and sensors; bank 2 is the side without cylinder 1.

What are the symptoms of P0432?

If your vehicle has triggered P0432, you may notice one or more of these symptoms:

Check engine light illuminated
Slight drop in fuel economy
Rotten-egg sulfur smell from exhaust
Possible rattling from under the Bank 2 side of the car (substrate breaking up)
Failed emissions or periodic technical inspection

What causes P0432?

Here are the most common causes of P0432:

Failing or worn main catalytic converter on Bank 2
: high
Faulty downstream O2 sensor (Bank 2, Sensor 2) with sluggish switching
: medium
Exhaust leak between pre-cat and main cat on Bank 2
: medium
Prior misfire on Bank 2 cylinders damaging the converter brick
: low
Oil consumption on Bank 2 fouling the substrate
: low

Is it safe to drive with P0432?

Generally yes, for short-term driving. Safe for normal driving. A lit engine warning light is checked at the periodic roadworthiness inspection in most EU countries and can be recorded as a deficiency, which may result in a failed inspection; each country applies its own rules. If rattling appears from under the floor on the Bank 2 side, the converter substrate may be breaking apart and replacement should be prioritised.

How do you diagnose P0432?

Follow these steps to pinpoint the root cause of P0432:

Confirm the engine actually has a Bank 2 with its own catalysts (V engines, boxers and some split-exhaust inline-sixes). On a single-bank engine P0432 points to a wiring fault or a misread code
Read freeze frame data and check for companion codes (P0431, P0430, Bank 2 misfires, Bank 2 lean or rich)
Inspect the full Bank 2 exhaust run for leaks, particularly at flange joints, slip-fit connectors, and flex pipe sections
Graph the Bank 2 downstream O2 sensor at steady 2,000 to 2,500 RPM. A healthy main cat keeps it stable around 0.4 to 0.6 V
Compare Bank 1 vs Bank 2 fuel trims. If Bank 2 long-term fuel trim runs consistently higher than Bank 1, the underlying mixture imbalance may be degrading the Bank 2 cat

How much does P0432 cost to fix?

Repair costs for P0432 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Replace main catalytic converter (Bank 2)	€240–€1500	€100–€300	€340–€1800	Professional
Replace downstream O2 sensor (Bank 2)	€55–€170	€70–€150	€125–€320	Moderate
Fix exhaust leak on Bank 2 (gasket or pipe section)	€30–€130	€100–€240	€130–€370	Moderate

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

P0432 on specific vehicles

P0432 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0432 on BMW

BMW 3 Series

See BMW-specific causes & cost

P0432 on Volkswagen

Volkswagen Touareg

See Volkswagen-specific causes & cost

Audi

Audi A6

2005-2024

On the Audi A6 3.0 TFSI (EA837) V6 each bank has its own catalysts, and P0432 points to the Bank 2 main cat. Check oil consumption and misfire history before condemning it, because either can shorten the life of a replacement.

P0432 on Mercedes-Benz

Mercedes-Benz E-Class

See Mercedes-Benz-specific causes & cost

These codes are often seen alongside P0432 or indicate related issues:

Common questions about P0432

What is the difference between P0430 and P0432?: Both are Bank 2 catalyst efficiency codes. P0430 is the generic OBD-II code used by most manufacturers. P0432 is used by some manufacturers (commonly Chrysler-Jeep and some European brands) to specifically label the main catalyst when the exhaust has a separate warm-up pre-cat and main cat per bank. The diagnostic approach is essentially identical.
Can I replace just the Bank 2 main cat and leave Bank 1 alone?: Yes, if Bank 1 shows no efficiency codes and the downstream O2 sensor traces look healthy. On a high-mileage engine the Bank 1 cat has the same age and duty, so it is worth having it checked while the car is up; replacing both at once can save overlapping labour if Bank 1 is also near the end.
Why does only Bank 2 fail when both banks have the same mileage?: Asymmetric wear is common. Causes include intake manifold geometry that delivers a slightly different air-fuel ratio per bank, exhaust packaging that traps more heat on one side, or a single failing injector or coil that has been quietly causing partial misfires on Bank 2 for months.
Will an aftermarket Bank 2 main cat pass emissions?: A replacement main cat has to hold enough oxygen for the catalyst monitor to pass it. Choose one specified for your exact engine and carrying EU type approval (an E-mark), rather than a universal converter that is not matched to the engine, which may not pass the monitor and can set P0432 again.

Read our detailed guides

Scan your car with Skanyx to diagnose P0432

Your car logged P0432. Skanyx reads it on a standard OBD2 adapter (Bluetooth LE on iPhone), tells you whether it is safe to keep driving, and shows the €125-€1800 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.