P0305 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Not safe to drive
P0305 on a BMW means the ECU counted enough missed combustion events on cylinder 5 to trip the misfire monitor. Expect rough running and a flashing check engine light under load.
- Severity
- High · Misfire
- Typical repair cost, all makes
- €45-€2700
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your BMW and Skanyx tells you what P0305 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 P0305 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 P0305.
BMW 3-Series E90/E92 (N54, N55)
2006-2013
On the 335i, the N54 (twin-turbo, 2006-2010) and N55 (single-turbo, 2010-2013) are inline-sixes. Check the cylinder 5 coil and spark plug first with the coil swap test. BMW recalled the N54 high-pressure fuel pump on US cars because of driveability problems, so low fuel pressure is worth checking if the misfire only shows under load.
Source: en.wikipedia.org, en.wikipedia.org
Sources
- en.wikipedia.org en.wikipedia.org/wiki/BMW_N54
- en.wikipedia.org en.wikipedia.org/wiki/BMW_N55
What causes P0305 on a BMW?
Beyond the generic causes listed on the main P0305 page, these are the patterns noted for BMW models:
Ignition coil failure on cylinder 5 (the other coils are the same age, so check them too)
: BMW 3-Series E90/E92 (N54, N55)
High-pressure fuel pump fault dropping rail pressure under load (N54)
: BMW 3-Series E90/E92 (N54, N55)
How to diagnose P0305 on a BMW with OBD2
- Read all stored and pending codes. Note fuel trims and any lean/rich codes (P0171, P0174) that could point at a vacuum or injector issue.
- Pull the coil and plug from cylinder 5. Fouled electrode, cracked insulator, or oil in the plug well tells you a lot before you swap anything.
- Swap the cylinder 5 coil with a neighbouring cylinder, clear codes, and drive. If the code moves (e.g. becomes P0303), replace the coil.
- Swap the injector connector or the injector itself with a neighbour if the coil swap didn't move the misfire. A noid light confirms the ECU is pulsing the injector.
- Check live fuel trims and misfire counters with a scan tool. Positive trim on the affected bank points to vacuum leak or weak injector flow.
- Smoke-test the intake if trims are lean. Cracked PCV hoses and split intake boots are common culprits.
- Compression test cylinder 5. More than 15% below the average of the other cylinders points to mechanical trouble. Follow up with a leakdown to isolate valves vs rings.
- After repair, clear codes and complete a misfire monitor drive cycle before declaring victory.
How much does P0305 cost to fix on a BMW? (EUR)
Estimated repair costs for P0305 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 |
|---|---|---|---|---|
| Replace spark plug on cylinder 5 (usually do the full set) | €15–€80 | €30–€120 | €45–€200 | Easy |
| Replace ignition coil on cylinder 5 | €40–€180 | €30–€90 | €70–€270 | Easy |
| Replace or ultrasonically clean fuel injector on cylinder 5 | €80–€350 | €100–€300 | €180–€650 | Moderate |
| Intake manifold gasket replacement to fix a vacuum leak | €40–€150 | €150–€400 | €190–€550 | Moderate |
| Cylinder head work after failed compression/leakdown (valve job or head R&R) | €300–€1200 | €400–€1500 | €700–€2700 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P0305
These codes are often seen alongside P0305 or point to related issues, on any make:
Looking for the full P0305 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0305 guide