P0432: Catalyst 2 Efficiency Below Threshold (Bank 2)
P0432 means the second catalytic converter on bank 2 (the engine side without cylinder 1) no longer cleans the exhaust well enough. It usually does not cause an immediate breakdown, but it turns on the check engine light and can cause an emissions test failure.
You can drive, but get it checked soon
The data lists no limp mode for this code, so the car normally keeps running. The fault is emissions-relevant and the light stays on, so have it checked soon. If the light flashes or the car runs rough, there may be a misfire, and that needs prompt attention.
What it means
A catalytic converter is an exhaust part that converts harmful gases into less harmful ones. On engines with two exhaust lines, each line can have a close-coupled catalyst near the engine and a main (underfloor) catalyst behind it. P0432 refers to that second one, the main or underfloor catalyst, on bank 2. The engine computer checks how well it converts exhaust, and it sets this code when the conversion falls below the required level. Bank 1 has a matching code, P0422. The data notes that no manufacturer document available to us uses this code, so it only applies to engines built with this two-catalyst layout on each side.
Likely causes
- Main or underfloor catalyst aged or poisonedVery likely
Catalysts wear out over time or get contaminated, and then they convert less of the exhaust.
- Diesel: exhaust fuel injector coked, doses too littlePossible
On diesels with an exhaust fuel injector, carbon buildup can reduce the fuel dosed into the exhaust, so the catalyst does not get the conditions it needs.
- Temperature or oxygen sensor after the catalyst wrongPossible
The computer judges the catalyst from sensor readings, so a faulty sensor can make a good catalyst look bad.
- Misfire or mixture fault as prior damageLess likely
Past misfires or a wrong fuel mixture can damage the catalyst, which then shows up as this code.
What you may notice
- Check engine light on
- Emission test problems
- Diesel: possibly more frequent filter regenerations
What to check, cheapest first
- 1Read the stored codes and note whether related codes such as P0422, P0431, P0430 or P0420 are also present. · you can do it
- 2Look for other codes about misfires or fuel mixture, and fix those first, since they can damage a catalyst. · you can do it
- 3Check the exhaust visually for damage, leaks or loose connections near the catalyst on bank 2. · you can do it
- 4Check the live readings of the sensor after the catalyst (oxygen or temperature) to see whether it behaves plausibly. · mechanic
- 5On a diesel, inspect the exhaust fuel injector for coking and check its dosing. · mechanic
- 6If the sensors and engine check out, replace the main catalyst on bank 2, then clear the code and complete a drive cycle to confirm the repair. · mechanic
Related codes
Frequently asked questions
Can I keep driving with P0432?+
Usually yes for a short time, since limp mode is not expected with this code. Get it checked soon, and avoid driving if the car runs rough or the light flashes.
Can a loose gas cap cause P0432?+
The data does not list the gas cap as a cause. The code points to the catalyst, its sensors, or earlier engine damage.
Will P0432 pass an emissions test?+
Probably not. The code is emissions-relevant and turns on the check engine light, which commonly leads to a failed test until it is repaired.
Can I fix P0432 myself?+
The data rates the repair as medium difficulty, estimates 1 to 3 hours, and does not consider it a good DIY job. Reading codes and a visual check are reasonable to do yourself.
Written with the help of AI from the public OBDex definition (CC0). Each make may use the code differently. Updated: 2026-11-10