CarSenseTrouble codes › P0305

P0305: Cylinder 5 Misfire Detected

What this check-engine code means in plain English, what usually causes it, and what a fix typically costs.

Severity: Urgent — can cause catalytic converter damage if driven extensively

What P0305 means

The engine control module has detected that cylinder 5 is not firing properly or consistently. A misfire means the air-fuel mixture in that cylinder isn't igniting correctly, causing rough running, reduced power, and increased emissions.

What causes P0305?

Likely
Faulty spark plug or ignition coilWorn spark plugs or a failing ignition coil on cylinder 5 are the most common causes of single-cylinder misfires.
Likely
Fuel injector problemA clogged or malfunctioning fuel injector for cylinder 5 can prevent proper fuel delivery and cause misfires.
Possible
Vacuum leak or intake gasketA vacuum leak near cylinder 5 or a leaking intake manifold gasket can create a lean condition causing misfires.
Less common
Low compression or mechanical issueWorn piston rings, valves, or head gasket problems in cylinder 5 can cause low compression and persistent misfires.

Is P0305 safe to drive?

Drive it?
Short distances okay, but address promptly
Watch for
Rough idle, hesitation, or check engine light flashing
DIY-friendly?
Spark plug replacement is DIY-friendly; coil swapping can help diagnose

You can drive short distances, but continued driving with a misfire can damage the catalytic converter (an expensive repair) and reduce fuel economy. If the check engine light is flashing, this indicates severe misfires and you should stop driving immediately to prevent catalytic converter damage.

P0305 repair cost

~$100 – $1000+

Industry-average estimates. Cost depends on the cause: spark plugs are inexpensive, but fuel injectors, ignition coils, or internal engine repairs cost significantly more.

Which one is it for your car?

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