P0307 on BMW: How to Diagnose & Fix
Cylinder 7 Misfire Detected
1 BMW model · 1 documented issue · $300-$2,400 repair
P0307 on BMW by model: symptoms, diagnosis and fix
The N63's direct injectors sit in the hottest part of a hot-vee engine and fail early, either leaking down and washing the cylinder or losing flow entirely. The result is a persistent misfire isolated to one cylinder that follows the injector when you swap it to another bore - the diagnostic that separates an injector from a coil, plug, or HPFP problem. BMW went through several injector revisions and ran an index-level campaign, replacing early injectors with index 11 or higher on affected cars; checking the index number stamped on each injector is a standard step when diagnosing N63 misfires. Owners on BimmerFest report chasing a cylinder-specific misfire through coils, plugs and even swapped high-pressure fuel pumps before the injector proved to be the culprit.
Common Symptoms
- Rough idle
- Persistent misfire on one cylinder
- Check engine light flashing under load
- Fuel smell from the exhaust
- Reduced power / engine malfunction message
How to Fix
Read the misfire counters per cylinder, then swap the suspect injector to a different cylinder - if the misfire moves, the injector is bad. Check the injector index level; anything below the current index should be updated. Injectors must be coded to the DME with their calibration numbers after replacement, and BMW specifies new decoupling elements and Teflon seals. Many N63 injector replacements have been covered free of charge under BMW's extended injector program, with a 2-year warranty on the replaced parts even on out-of-warranty cars - ask the dealer before paying. Replace plugs at the same time since the washed cylinder has fouled them.
Sources for this issue (3)
P0307 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 P0307 mean on a BMW?
P0307 stands for "Cylinder 7 Misfire Detected." P0307 means the engine computer detected a misfire on cylinder number 7 — that cylinder isn't burning its air/fuel mixture completely or at the right moment. The PCM senses this by watching for tiny slowdowns in crankshaft speed each time cylinder 7 should fire. A misfire wastes fuel, can dump raw fuel into the exhaust, and may damage the catalytic converter over time, which is why a persistent or severe misfire often makes the check engine light flash. You may feel rough idle, shaking, hesitation, or a loss of power. On BMW it is documented across 1 model: 7 Series.
What are the most common causes of P0307?
The most common causes of P0307 are: Worn, fouled, or incorrectly gapped spark plug on cylinder 7, Failed ignition coil or coil-on-plug for cylinder 7, Faulty, clogged, or leaking fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/leaking valve, head gasket), Damaged spark plug wire or boot (on applicable engines), Carbon buildup or sticking valve. The specific cause varies by vehicle.
How much does it cost to fix P0307 on a BMW?
Published repair estimates on BMW range from $300 to $2,400 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0307 on a different make?
View P0307 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.