P0430 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Safe to drive (short-term)
P0430 on a BMW means the catalytic converter on Bank 2 (the engine bank that does not contain cylinder 1, found on V6, V8 and boxer engines, and on some inline-sixes that split their exhaust into two halves with a converter each) is no longer cleaning exhaust gases efficiently. The ECU detects this by comparing the upstream and downstream oxygen sensors: a healthy converter keeps the rear sensor steady, a worn one lets it swing. The most common cause is a worn-out converter at high mileage, costing roughly 300 to 1,900 EUR to replace depending on the type.
- Severity
- Moderate · Emissions
- Typical repair cost, all makes
- €100-€1900
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your BMW and Skanyx tells you what P0430 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat does P0430 mean on a BMW?
The Quick Answer above is the generic definition. What follows is the model-specific detail for the BMW models that log P0430.
BMW 3 Series
2006-2024
BMW's N52 and N54 inline-sixes have two exhaust manifolds, each with its own catalytic converter and oxygen sensors, and the engine computer treats cylinders 1 to 3 as Bank 1 and cylinders 4 to 6 as Bank 2, so they can set a genuine P0430 for the rear half of the engine. On the N52 the converters are built into the exhaust manifolds, which pushes parts cost toward the high end. The V8 E90/E92 M3 (S65) also has a Bank 2 converter. Rich running from VANOS or fuel-trim faults can degrade the Bank 2 converter early.
Source: ge39.com, bimmerworld.com
Sources
- ge39.com ge39.com/files/m54x5.pdf
- bimmerworld.com bimmerworld.com/Exhaust/O2-Sensors/BMW-Engine-Oxygen-Sensor-O2-11787545074.html
What causes P0430 on a BMW?
Beyond the generic causes listed on the main P0430 page, these are the patterns noted for BMW models:
Manifold-integrated Bank 2 converter (cylinders 4 to 6) on the N52, raising replacement cost
: BMW 3 Series
VANOS or fuel-trim faults causing rich running that accelerates Bank 2 converter wear
: BMW 3 Series
How to diagnose P0430 on a BMW with OBD2
- Check for companion codes first (misfires, lean/rich trims, O2 heater faults). Fix those before P0430, as the catalyst code is often secondary to a misfire or fuel-mixture problem
- Graph the Bank 2 upstream and downstream O2 sensors at steady cruise (2,000 to 2,500 RPM). The upstream sensor should oscillate 0.1 to 0.9V rapidly. The downstream should stay fairly flat around 0.4 to 0.6V on a healthy converter
- If the downstream sensor mirrors the upstream oscillations, the converter is no longer storing oxygen and is likely failing
- Test the downstream O2 sensor response. If switching lean-to-rich or rich-to-lean takes over 300ms, the sensor itself is sluggish and may be the real cause rather than the converter
- Inspect the Bank 2 exhaust manifold, converter flanges, and piping for leaks. Listen for ticking or hissing on a cold start and check for soot around joints
- On high-mileage engines, check oil consumption and look for coolant loss. Burning oil or coolant contaminates the converter and will quickly kill a new one if not addressed
- Confirm you are working on the correct bank: Bank 2 is the side that does not contain cylinder 1. Verify cylinder 1 location in the service manual before condemning a converter
How much does P0430 cost to fix on a BMW? (EUR)
Estimated repair costs for P0430 in EUR, compiled across makes. Expect BMW parts and labour towards the upper end of each range.
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace downstream O2 sensor (Bank 2) | €50–€150 | €60–€120 | €110–€270 | Moderate |
| Fix exhaust leak / replace gasket | €20–€100 | €80–€200 | €100–€300 | Moderate |
| Replace catalytic converter (standard) | €200–€800 | €100–€300 | €300–€1100 | Professional |
| Replace catalytic converter (integrated manifold type) | €500–€1500 | €200–€400 | €700–€1900 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P0430
These codes are often seen alongside P0430 or point to related issues, on any make:
Looking for the full P0430 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0430 guide