The Quick Answer above is the generic definition. What follows is the model-specific detail for the BMW models that log P0405.
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.
Typical repair cost, all makes€70 - €670
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Get Skanyx freeWhat 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 patterns noted for BMW models:
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 for P0405 in EUR, compiled across makes. Expect BMW parts and labour towards the upper end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0405
These codes are often seen alongside P0405 or point to related issues, on any make:
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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