The Quick Answer above is the generic definition. What follows is the model-specific detail for the Mercedes-Benz models that log P0306.
DTC/P0306·Mercedes-Benz
P0306 on Mercedes-Benz: Causes, Symptoms and Fix Cost
Quick Answer
High SeverityNot safe to driveMercedes-Benz
P0306 on a Mercedes-Benz 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.
Typical repair cost, all makes€38 - €2300
Connect any standard Bluetooth OBD2 adapter to your Mercedes-Benz and Skanyx tells you what P0306 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
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Mercedes C-Class
2008-2018W204 C350 with the M272 V6 can log P0306 from a worn cylinder 6 ignition coil or spark plug. Cylinder 6 is the last cylinder of bank 2, so also check for vacuum leaks at the rear of the intake manifold on that side.
What causes P0306 on a Mercedes-Benz?
Beyond the generic causes listed on the main P0306 page, these are the patterns noted for Mercedes-Benz models:
Mercedes C-ClassCylinder 6 coil or spark plug wear on M272 V6
Mercedes C-ClassVacuum leak at the rear of the bank 2 intake
How to diagnose P0306 on a Mercedes-Benz 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 Mercedes-Benz? (EUR)
Estimated repair costs for P0306 in EUR, compiled across makes. Expect Mercedes-Benz parts and labour towards the upper end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0306
These codes are often seen alongside P0306 or point to related issues, on any make:
Looking for the full P0306 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0306 guideSkanyx · Mercedes-Benz
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