Drivable short-term, but fix now to avoid damage.
P0304 means the engine computer detected a misfire in cylinder number 4. That cylinder isn't igniting its air-fuel mixture properly, so the engine runs rough and loses power. Being cylinder-specific, the cause is usually a worn ignition or fuel component on cylinder 4.
$80 – $450
Varies by vehicle and root cause.
Only briefly and gently. If the engine light is flashing, stop and have the car towed to avoid expensive catalytic converter damage.
Usually $80-$300 for a spark plug or coil on cylinder 4 with labor. Injector or compression repairs can push it toward $450 or more.
It can be. A continuing misfire risks overheating and ruining the catalytic converter, so it's wise to fix it without much delay.
A single-cylinder code usually means a part dedicated to that cylinder, like its coil, plug, or injector, has worn out or failed, rather than an engine-wide problem.