P0306 on a Ford: 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 Ford

On a Ford, P0306 means the engine computer detected that cylinder 6 is misfiring, so that cylinder is not firing and producing power on schedule. Ford V6 engines like the 3.5L EcoBoost use one ignition coil per cylinder, so the fault usually comes down 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 Fords?

P0306 shows up on Ford V6 models like the F-150 with the 3.5L EcoBoost, the Explorer, and the Edge, often with higher mileage or heavy towing use. Ignition coils and spark plugs are the usual wear items on these engines, and EcoBoost coil failures are a well-known pattern. Fuel injector issues and low compression are less common causes.

Commonly reported on: F-150, Explorer, Edge, Mustang.

Symptoms

Check engine light on (flashing if severe)
Rough idle or shaking while idling
Loss of power or hesitation under load
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	$80–350
Replace worn spark plugs	Yes	$60–250
Replace or clean the cylinder 6 fuel injector	Mechanic	$150–400
Run a compression test to rule out internal engine wear	Mechanic	$100–200