P0305: Cylinder 5 Misfire Detected

What P0305 means

The computer has counted repeated misfires in cylinder 5. It detects this by watching for a small dip in crankshaft speed each time cylinder 5 should fire.

Because the problem is isolated to one cylinder, the cause is usually a part that serves only that cylinder: its spark plug, ignition coil, or fuel injector. Less often it is a mechanical problem such as a leaking valve.

Cylinder 5 only exists on engines with five or more cylinders. On inline six engines it is second from the rear, near the firewall end. On V6 and V8 engines, manufacturers number cylinders differently: some put all odd numbers on one bank, others count straight down one bank and then the other. Check the diagram for your engine before replacing parts.

Which physical cylinder is number 5 depends on the engine. Your owner manual or a service manual shows the firing order layout. Do not guess on V engines, where numbering differs between manufacturers.

Common causes (cheapest likely first)

1. Worn or fouled spark plug in cylinder 5. The cheapest likely fix. Check the gap and look for oil or carbon fouling.
2. Failing ignition coil. The classic test is to swap the coil with a neighboring cylinder. If the misfire follows the coil to a new cylinder number, the coil is bad.
3. Damaged plug wire or coil boot. Cracked boots let spark jump to the cylinder head instead of the plug.
4. Clogged or leaking fuel injector. If the misfire stays with the cylinder after swapping coils and plugs, the injector is next.
5. Low compression in that cylinder. A burnt valve, worn rings, or head gasket leak. A compression test confirms it.

Symptoms

• Flashing or steady check engine light
• Rough idle, often felt as a rhythmic shake
• Hesitation when accelerating
• Loss of power
• Fuel smell

DIY difficulty: Easy to moderate

Swapping a coil or plug is a good first DIY job when the cylinder is easy to reach. Rear cylinders on V engines can be hidden under the intake.

Tools: OBD-II scanner, Spark plug socket, Torque wrench, Dielectric grease, Compression tester for deeper checks

Cylinder 5 access and tips

• Cylinder 5 only exists on engines with five or more cylinders. On inline six engines it is second from the rear, near the firewall end.
• On V6 and V8 engines, manufacturers number cylinders differently: some put all odd numbers on one bank, others count straight down one bank and then the other. Check the diagram for your engine before replacing parts.
• If P0305 appears with misfires on other cylinders of the same bank, check for a shared cause such as a vacuum leak or a bank specific fuel problem.
• Mark the coil before swapping it to another cylinder so you can track which part moves where.

Estimated repair cost

This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.

Watch a repair video

Search YouTube for “P0305 fix” videos. Pick a recent video that matches your engine, and confirm the diagnosis before buying parts.

By make

This code works the same way on every make. See brand notes.

Related codes

• P0300Random or Multiple Cylinder Misfire Detected
• P0306Cylinder 6 Misfire Detected
• P0301Cylinder 1 Misfire Detected
• P0302Cylinder 2 Misfire Detected
• P0420Catalyst System Efficiency Below Threshold (Bank 1)

Check for recalls

Before paying for a repair, enter your VIN in the NHTSA recall lookup. Emissions parts may also be covered by a federal emissions warranty; check your warranty booklet.

FAQ