P0433 means the electrically heated catalyst on Bank 2 (an e-cat with an integrated resistive heating element used on newer Euro 6 and 6d vehicles to reach light-off temperature within seconds of start) is not converting emissions efficiently. It only applies to multi-bank engines, so V6, V8, V10, V12, or flat configurations.
DTC/P0433·BMW
P0433 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)BMW
P0433 on a BMW means the electrically heated catalyst on Bank 2 (an e-cat with an integrated resistive heating element used on newer Euro 6 and 6d vehicles to reach light-off temperature within seconds of start) is not converting emissions efficiently. It only applies to multi-bank engines, so V6, V8, V10, V12, or flat configurations.
Repair cost on BMW€182 - €3584
What does P0433 mean on a BMW?
BMW 3 Series
2020-2024P0433 on the G20 3 Series applies to the M3 (S58 twin-turbo inline-6) and high-output xDrive variants that received Bank 2 e-cat hardware as part of Euro 6d-Full compliance from 2020 onward. The S58 has a per-bank heated pre-cat assembly, and Bank 2 e-cat failure is documented after 80,000 km on cars used in heavy start-stop urban driving. BMW often replaces the entire manifold-and-e-cat assembly under emissions warranty.
What causes P0433 on a BMW?
Beyond the generic causes listed on the main P0433 page, these are the BMW-specific patterns we see most often:
BMW 3 SeriesS58 Bank 2 e-cat heater element failure after 80,000 km in start-stop use
BMW 3 SeriesManifold-integrated assembly requires full unit replacement under warranty
How to diagnose P0433 on a BMW with OBD2
Follow these steps to pinpoint the root cause of P0433:
- Confirm the engine is multi-bank (V6, V8, V10, V12, or flat). P0433 on an inline engine indicates scan-tool or wiring error
- Read freeze frame and confirm the code triggered shortly after cold start, which is typical of heated catalyst faults
- Check for companion heater-circuit codes such as P0432, P0434, or manufacturer-specific heater faults
- Measure resistance of the Bank 2 e-cat heater element per OEM spec (typical 0.3 to 2.0 ohms)
- Graph Bank 2 downstream O2 sensor during cold start. A healthy heated cat stabilises within 20 to 40 seconds
How much does P0433 cost to fix on a BMW? (EUR)
Estimated repair costs on a BMW (BMW parts and labour typically run 40% above the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0433 on BMW
These codes commonly cluster with P0433 on BMW vehicles:
FAQ: P0433 on BMW
Which engines actually have a heated catalyst on Bank 2?
Heated catalysts on Bank 2 appear on Euro 6d and 6d-Full multi-bank engines from roughly 2019 onward, especially mild-hybrid 48V V6 and V8 powertrains. Examples include Audi 3.0 TFSI (EA839), Mercedes M256 inline-6, BMW B58 in mild-hybrid spec, and Mercedes M177 V8 in late C63 and E63 variants. Older non-hybrid V6 and V8 engines typically do not have e-cats.
Why does only Bank 2 set P0433 when both banks have e-cats?
The two banks have separate heater circuits and separate downstream O2 sensors. If a single wire, connector, or heater element fails on Bank 2 alone, only Bank 2 will set the code. Fuel-trim asymmetry between banks (caused by intake manifold geometry or injector wear) can also age one bank's heated cat faster than the other.
Can a 48V mild-hybrid system fault trigger P0433?
Yes. The e-cat heater is supplied by the 48V network on most modern mild-hybrid platforms. A weak 48V battery, a degraded DC-DC converter, or an integrated starter-generator output fault can starve the Bank 2 heater of current and trigger P0433. Always test the 48V system health before replacing the catalyst itself.
Will my warranty cover a P0433 repair?
Emissions components in the EU typically carry an extended emissions warranty of five years or 100,000 km, sometimes longer. Heated catalysts qualify under this warranty on most manufacturers. Check your service book or dealer for the specific terms before paying for an out-of-warranty replacement.
Looking for the full P0433 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0433 guideSkanyx · BMW
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