P2187 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Safe to drive (short-term)
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.
- Severity
- Moderate · Fuel System
- Typical repair cost, all makes
- €35-€380
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your BMW and Skanyx tells you what P2187 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 P2187 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 P2187.
BMW 3 Series
2005-2024
On the E90 with the naturally aspirated N52, unmetered air at idle often comes from the crankcase ventilation system, the oil filler cap seal or the dipstick tube seal, and higher-output N52 versions also have a DISA intake valve whose seal can leak. The turbocharged N55 has no DISA valve, so on those cars look at the crankcase ventilation, the intake and the charge pipes instead.
Source: en.wikipedia.org, en.wikipedia.org
Sources
- en.wikipedia.org en.wikipedia.org/wiki/BMW_N52
- en.wikipedia.org en.wikipedia.org/wiki/BMW_N55
What causes P2187 on a BMW?
Beyond the generic causes listed on the main P2187 page, these are the patterns noted for BMW models:
Crankcase ventilation (CCV) system leak on N52
: BMW 3 Series
DISA valve seal leak on higher-output N52
: BMW 3 Series
Oil filler cap gasket and dipstick tube leaks
: BMW 3 Series
How to diagnose P2187 on a BMW with OBD2
- 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 a usual cause and is 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 for P2187 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 |
|---|---|---|---|---|
| Vacuum hose replacement | €5–€30 | €40–€120 | €45–€150 | Easy |
| MAF sensor cleaning or replacement | €15–€180 | €20–€60 | €35–€240 | Easy |
| Intake manifold gasket replacement | €20–€80 | €100–€300 | €120–€380 | Moderate |
| Fuel injector seal replacement | €15–€60 | €80–€200 | €95–€260 | Moderate |
| PCV valve replacement | €20–€100 | €40–€150 | €60–€250 | Easy |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P2187
These codes are often seen alongside P2187 or point to related issues, on any make:
Looking for the full P2187 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P2187 guide