P0405 means the EGR position sensor 'A' (the primary feedback sensor on the EGR valve) is sending a voltage below the normal operating range, typically below 0.2V. This is almost always a wiring fault, a corroded connector, or a sensor that has failed shorted to ground.
DTC/P0405·BMW
P0405 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)BMW
P0405 on a BMW means the EGR position sensor 'A' (the primary feedback sensor on the EGR valve) is sending a voltage below the normal operating range, typically below 0.2V. This is almost always a wiring fault, a corroded connector, or a sensor that has failed shorted to ground.
Repair cost on BMW€98 - €938
What does P0405 mean on a BMW?
BMW 3 Series
2007–2024The N47 and B47 320d EGR position sensor sits in a heat-soaked location near the turbo, and is integrated into the EGR valve. P0405 typically appears around 120,000 km, often after the connector seal degrades and lets moisture in. INPA or ISTA can confirm the sensor voltage in the live data screen. Always reset adaptation values after valve replacement.
What causes P0405 on a BMW?
Beyond the generic causes listed on the main P0405 page, these are the BMW-specific patterns we see most often:
BMW 3 SeriesN47/B47 integrated position sensor degradation from heat soak
BMW 3 SeriesConnector seal failure allowing moisture into Hall sensor
How to diagnose P0405 on a BMW with OBD2
Follow these steps to pinpoint the root cause of P0405:
- Back-probe the sensor signal wire with the key on, engine off. A healthy sensor at rest should read 0.5–1.0V (varies by vehicle, check workshop spec)
- Verify 5V reference at the sensor connector. If reference is missing, trace the wire back toward the ECU
- Unplug the sensor connector and inspect for water intrusion, corrosion, and bent pins
- With the connector unplugged, the signal wire should read 5V at the ECU side. If it reads 0V, the wire is shorted to ground
- If wiring and reference are good, the sensor itself is the most likely failure. On most modern systems, replacing the integrated valve assembly is the practical fix
How much does P0405 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 P0405 on BMW
These codes commonly cluster with P0405 on BMW vehicles:
FAQ: P0405 on BMW
Can I drive with P0405?
Short distances yes. The ECU disables EGR control when the position sensor signal is unreliable, so the engine runs without EGR (more NOx, more pinging on petrol, possible limp mode on diesel). Resolve within a couple of weeks to avoid intake carbon buildup and emissions test failure.
Is P0405 the sensor or the wiring?
About 60% of the time it is the integrated sensor failing inside the EGR valve. The other 40% is wiring or connector corrosion. Always inspect the connector and measure the 5V reference at the sensor before condemning the valve, since wiring repairs are far cheaper.
Can I just replace the EGR sensor without the valve?
On older vehicles with separate DPFE sensors (older Fords, some Japanese makes), yes. On modern BMW, Mercedes, and VAG vehicles the sensor is integrated into the EGR valve and not available separately. You replace the whole valve assembly.
Why is the EGR position sensor failing on my diesel?
Diesel EGR valves run hot and dirty. The position sensor sits directly on the valve, so it sees constant thermal cycling and soot. Hall-effect sensors degrade over time, and the connector seals fail. Failure between 100,000–150,000 km is typical on BMW N47/B47 and VW EA189/EA288.
Looking for the full P0405 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0405 guideSkanyx · BMW
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