P0306 on a Mercedes-Benz: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

If the check engine light is flashing, stop driving — a severe misfire can damage the catalytic converter. A steady light is usually safe for a short drive to a shop.

What P0306 means on a Mercedes-Benz

On a Mercedes-Benz, P0306 means the engine computer detected that cylinder 6 is misfiring, so that cylinder is not producing power on schedule. Mercedes V6 engines use one ignition coil per cylinder, so the fault usually points to cylinder 6's coil, plug, or injector. A flashing light means the misfire is severe enough to risk catalytic converter damage.

Is P0306 common on Mercedes-Benzs?

P0306 appears on Mercedes V6 models like the C-Class, E-Class, and GLK, most often as the engine accumulates miles. Ignition coils and spark plugs are the usual wear items on the M272 and M276 engines, and the coils sit deep in the V where they run hot. Fuel injector issues and engine wear are less common causes.

Commonly reported on: C-Class, E-Class, GLK, GLE.

Symptoms

Check engine light on (flashing if severe)
Rough idle or vibration while idling
Loss of power or hesitation when accelerating
Poor fuel economy

Common causes

most common: Failing ignition coil on cylinder 6
common: Worn or fouled spark plug in cylinder 6
common: Clogged or leaking fuel injector on cylinder 6
less common: Damaged wiring or connector at the cylinder 6 coil
rare: Low compression in cylinder 6 from engine wear

How to fix it

Fix	DIY?	Typical cost
Replace the ignition coil on cylinder 6	Yes	$100–400
Replace worn spark plugs	Yes	$80–300
Replace or clean the cylinder 6 fuel injector	Mechanic	$200–500
Run a compression test to rule out internal engine wear	Mechanic	$100–250

Frequently asked questions

Is it safe to drive my Mercedes with a P0306 code?

Only if the light is steady and the car runs fine. A flashing light means a severe misfire, so stop and have it towed.

What causes P0306 on a Mercedes V6?

Ignition coils and spark plugs are the most common causes as the engine ages. The coils run hot inside the V, so they tend to fail before other parts.

How much does it cost to fix P0306 on a Mercedes-Benz?

Coil and plug fixes usually run $100–$400. Injector work and internal engine repairs cost more.