P0306 means the ECU has detected repeated misfires on cylinder 6. Because cylinder 6 only exists on engines with six or more cylinders, this code is found exclusively on inline-6, V6, V8, and larger configurations. Common culprits are an ignition coil or spark plug specific to cylinder 6, a clogged injector, or in rarer cases compression loss in that cylinder.
DTC/P0306·BMW
P0306 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
High SeverityNot safe to driveBMW
P0306 on a BMW means the ECU has detected repeated misfires on cylinder 6. Because cylinder 6 only exists on engines with six or more cylinders, this code is found exclusively on inline-6, V6, V8, and larger configurations. Common culprits are an ignition coil or spark plug specific to cylinder 6, a clogged injector, or in rarer cases compression loss in that cylinder.
Repair cost on BMW€53 - €3220
What does P0306 mean on a BMW?
BMW 3 Series
2005-2024The E90 330i with the N52 inline-six is famous for failing the cylinder 6 ignition coil first because of heat soak at the rear of the engine. BMW recommends replacing coils and plugs as a set at around 80,000 km. P0306 is one of the most common codes flagged on N52 in independent specialist shops.
What causes P0306 on a BMW?
Beyond the generic causes listed on the main P0306 page, these are the BMW-specific patterns we see most often:
BMW 3 SeriesCylinder 6 ignition coil heat-soak failure on N52 (rear position)
BMW 3 SeriesCylinder 6 injector wear on N54 twin-turbo
How to diagnose P0306 on a BMW with OBD2
Follow these steps to pinpoint the root cause of P0306:
- Read freeze-frame data and look at RPM, load, and coolant temperature when the misfire was logged. Cold-only misfires often point to fuel; hot-only misfires often point to ignition coils heat-soaking
- Swap the ignition coil from cylinder 6 with a coil from a healthy cylinder. Clear codes and drive. If the misfire follows the coil, replace it
- Remove the cylinder 6 spark plug and inspect for wear, fuel fouling, oil deposits, or a cracked porcelain. Replace any plug that looks suspect
- Listen to the cylinder 6 injector with a stethoscope. A weak or absent click points to electrical or mechanical injector failure
- Perform a compression test on cylinder 6 and compare to the others. A difference of more than 10% indicates an internal engine issue requiring deeper inspection
How much does P0306 cost to fix on a BMW? (EUR)
Estimated repair costs on a BMW (BMW parts and labour typically run 40% 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 P0306 on BMW
These codes commonly cluster with P0306 on BMW vehicles:
FAQ: P0306 on BMW
Why is the misfire only on cylinder 6?
A single-cylinder misfire code is the ECU telling you that one specific cylinder is contributing to crankshaft acceleration less than its neighbours. The cause is almost always something localised to that cylinder: its coil, plug, injector, or valves, rather than a problem that would affect the whole engine.
Can I drive with cylinder 6 misfiring?
Only as far as the nearest workshop, and ideally with a tow if the check engine light is flashing. A persistent misfire pumps unburned fuel into the catalytic converter, which can overheat and fail. Catalyst replacement is usually the most expensive part of fixing an ignored misfire.
Where is cylinder 6 on a V6 or inline-6?
On most inline-6 engines (BMW N52, N54, N55, B58), cylinder 6 is at the rear, closest to the firewall. On V6 engines the location depends on manufacturer numbering: on BMW V6 it is the rearmost cylinder on Bank 2, on most Toyota V6 it is the rearmost cylinder on Bank 1. Check a wiring diagram for your engine.
Why does the BMW N52 fail cylinder 6 first?
On the N52 inline-six, cylinder 6 sits at the back near the firewall where heat soak is highest. The ignition coil over cylinder 6 routinely fails before the others. Mechanics replace it as a pair (cylinders 5 and 6) when they see the first failure to avoid a repeat visit.
Looking for the full P0306 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0306 guideSkanyx · BMW
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