P0401 on BMW: How to Diagnose & Fix
Exhaust Gas Recirculation Flow Insufficient
1 BMW model · 1 documented issue · 1 critical
P0401 on BMW by model: symptoms, diagnosis and fix
The 740Ld xDrive uses the N57 inline-six diesel, whose EGR cooler can crack and leak coolant internally. The coolant mixes with diesel soot inside the EGR path, and at high EGR gas temperatures those wetted soot particles can smolder, melting the plastic intake manifold and creating a risk of underhood fire. NHTSA recall campaign 18V-755 (October 2018) covered 2013-2017 BMW diesels including the 2015 740Ld, and recall 21V-907 (November 2021) superseded and expanded it to roughly 50,400 vehicles, re-including every car previously covered by 18V-755. This is an active fire-risk recall, not a nuisance item.
Common Symptoms
- Unexplained coolant loss with no visible external leak
- White smoke from the exhaust
- Burning smell from the engine bay
- Reduced power or limp mode
- Check engine light
How to Fix
Take the VIN to a BMW dealer under recall 21V-907 - the repair is free. Dealers inspect and replace the EGR cooler; if a leak has already occurred, the intake manifold is replaced as well. Verify status by VIN at nhtsa.gov/recalls, since a car repaired under the earlier 18V-755 campaign is still covered by the 2021 expansion. Do not dismiss unexplained slow coolant loss with no external leak on an N57 diesel - that is the leading indicator.
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Sources for this issue (3)
P0401 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0401 mean on a BMW?
P0401 stands for "Exhaust Gas Recirculation Flow Insufficient." This code means the Exhaust Gas Recirculation (EGR) system is not flowing enough exhaust back into the engine. The EGR system recirculates a small amount of exhaust into the intake to lower combustion temperatures and reduce nitrogen oxide (NOx) emissions; the computer has determined the actual flow is below what it commanded. The most common reason is carbon buildup clogging the EGR valve or its passages. You may notice pinging/knocking, rough idle, or a check engine light, and the car will fail emissions testing. On BMW it is documented across 1 model: 7 Series.
What are the most common causes of P0401?
The most common causes of P0401 are: Carbon buildup clogging the EGR valve or passages, Stuck or faulty EGR valve, Blocked or restricted EGR ports/tubes, Faulty EGR temperature or position sensor, Faulty DPFE/EGR pressure sensor (on applicable systems), Vacuum leak or failed vacuum control (vacuum-operated EGR), Wiring or connector problems at the EGR valve. The specific cause varies by vehicle.
How much does it cost to fix P0401 on a BMW?
Repair costs vary widely with the root cause and BMW model; each issue on this page carries its own estimate where one is published.
Looking for P0401 on a different make?
View P0401 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.