P2187 means the engine is running too lean specifically at idle speed on Bank 1. The fuel system is not delivering enough fuel relative to the amount of air entering the engine at low RPM. This is different from P0171, which indicates a lean condition across all operating ranges.
DTC/P2187·BMW
P2187 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)BMW
P2187 on a BMW means the engine is running too lean specifically at idle speed on Bank 1. The fuel system is not delivering enough fuel relative to the amount of air entering the engine at low RPM. This is different from P0171, which indicates a lean condition across all operating ranges.
Repair cost on BMW€42 - €456
What does P2187 mean on a BMW?
BMW 3 Series
2005-2024The E90/F30 with N52 and N55 engines is prone to P2187 due to the DISA valve (intake manifold flap) failing and causing an internal vacuum leak. The valve cover CCV (crankcase ventilation) system on the N52 is also a common failure point. BMW-specific vacuum leaks also occur at the oil filler cap gasket and dipstick tube.
What causes P2187 on a BMW?
Beyond the generic causes listed on the main P2187 page, these are the BMW-specific patterns we see most often:
BMW 3 SeriesDISA valve failure causing internal vacuum leak
BMW 3 SeriesN52 CCV (valve cover crankcase vent) system failure
BMW 3 SeriesOil filler cap gasket and dipstick tube leaks
How to diagnose P2187 on a BMW with OBD2
Follow these steps to pinpoint the root cause of P2187:
- With the engine idling, listen carefully for any hissing or whistling sounds around the intake manifold, vacuum hoses, and PCV system. A vacuum leak is the most common cause and often audible.
- Use a smoke machine to pressurize the intake system and find vacuum leaks. Smoke will escape from any crack, split hose, or faulty gasket. Pay special attention to the intake manifold gasket and brake servo hose.
- Check the MAF sensor readings at idle using live data. Compare the actual airflow reading to the manufacturer's specification for your engine. A dirty MAF sensor will underreport airflow, causing the ECU to deliver too little fuel.
- Monitor short-term and long-term fuel trims at idle. Values above +10% confirm the ECU is adding fuel to compensate for a lean condition. If trims normalise at higher RPM, the leak is only significant at idle vacuum.
- If no vacuum leak or MAF issue is found, check fuel pressure at idle with a fuel pressure gauge. Low fuel pressure at idle but normal pressure at higher RPM can indicate a failing fuel pressure regulator or weak fuel pump.
How much does P2187 cost to fix on a BMW? (EUR)
Estimated repair costs on a BMW (BMW parts and labour typically run 20% 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 P2187 on BMW
These codes commonly cluster with P2187 on BMW vehicles:
FAQ: P2187 on BMW
What does P2187 mean?
P2187 means your engine is running too lean (too much air relative to fuel) specifically at idle speed on Bank 1. The ECU has detected that it needs to add more fuel than expected to maintain the correct air-fuel ratio at idle.
What is the difference between P0171 and P2187?
P0171 indicates a lean condition across all engine operating conditions, while P2187 is lean only at idle. P2187 strongly suggests a vacuum leak, since vacuum leaks have the most effect at idle when airflow is lowest and manifold vacuum is highest.
Can a vacuum leak cause P2187?
Yes, a vacuum leak is the most common cause of P2187. At idle, engine vacuum is at its highest, so even a small leak allows significant unmetered air into the intake. A smoke test is the best way to find vacuum leaks.
Will cleaning the MAF sensor fix P2187?
It can. A contaminated MAF sensor underreads airflow, causing the ECU to deliver insufficient fuel. Cleaning with dedicated MAF sensor cleaner spray is a simple first step that costs under 10 EUR and takes 10 minutes.
Is it safe to drive with P2187?
Short-term driving is safe, but a persistent lean condition at idle causes rough running and can lead to catalytic converter overheating over time. Diagnose and repair the cause within a few weeks.
Looking for the full P2187 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P2187 guideSkanyx · BMW
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