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DTC/P0433

P0433: Heated Catalyst Efficiency Below Threshold (Bank 2)

Quick Answer
Moderate SeveritySafe to drive (short-term)Emissions

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.

Estimated repair costFrom €130 to €2560+, varies by vehicle

What does P0433 mean?

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.

P0433 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0433 and illuminates the check engine light.

What are the symptoms of P0433?

If your vehicle has triggered P0433, you may notice one or more of these symptoms:

  • Check engine light illuminated, often within the first minute after start
  • Elevated cold-start emissions on the Bank 2 side, visible on a cold morning
  • Slight reduction in fuel economy
  • Possible faint sulfur smell during warm-up
  • Failed emissions test or periodic technical inspection

What causes P0433?

Here are the most common causes of P0433, ranked by how likely they are to be the culprit:

highFailed Bank 2 e-cat heater element or substrate degradation
mediumFaulty downstream O2 sensor (Bank 2, Sensor 2)
mediumWiring or connector fault to the Bank 2 e-cat heater control module
lowPrior misfire on Bank 2 cylinders damaging the heated brick
lowOil consumption from Bank 2 fouling the substrate

Is it safe to drive with P0433?

Generally yes, for short-term driving. Safe for short-term driving. Heated catalyst codes typically appear on newer Euro 6 and 6d vehicles with electrically heated catalysts (e-cats). P0433 only applies to V6, V8, V10, V12, or flat-engine vehicles since Bank 2 must exist. Cold-start emissions will be elevated.

How do you diagnose P0433?

Follow these steps to pinpoint the root cause of P0433:

  1. Confirm the engine is multi-bank (V6, V8, V10, V12, or flat). P0433 on an inline engine indicates scan-tool or wiring error
  2. Read freeze frame and confirm the code triggered shortly after cold start, which is typical of heated catalyst faults
  3. Check for companion heater-circuit codes such as P0432, P0434, or manufacturer-specific heater faults
  4. Measure resistance of the Bank 2 e-cat heater element per OEM spec (typical 0.3 to 2.0 ohms)
  5. 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?

Repair costs for P0433 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair Parts Cost Labor Cost Total Estimate DIY Difficulty
Replace heated catalytic converter (Bank 2) €650–€2200 €140–€360 €790–€2560 Professional
Replace downstream O2 sensor (Bank 2) €65–€190 €70–€150 €135–€340 Moderate
Fix exhaust leak on Bank 2 (gasket or flex pipe) €30–€130 €100–€240 €130–€370 Moderate

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

P0433 on specific vehicles

P0433 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

BMW

P0433 on BMW

BMW 3 Series

See BMW-specific causes & cost
Volkswagen

P0433 on Volkswagen

Volkswagen Touareg

See Volkswagen-specific causes & cost
Audi

P0433 on Audi

Audi A6

See Audi-specific causes & cost
Mercedes-Benz

P0433 on Mercedes-Benz

Mercedes-Benz E-Class

See Mercedes-Benz-specific causes & cost

These codes are often seen alongside P0433 or indicate related issues:

P0420P0423P0430P0432P0434

Common questions about P0433

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.

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