Where is cylinder 8 located?

On GM V8s (Chevrolet, GMC), even-numbered cylinders sit on the right bank, so cylinder 8 is the rearmost cylinder on that side, next to the bulkhead. On Ford V8s the left bank carries cylinders 5 to 8, so cylinder 8 is the rearmost on the left. European V8s differ between makers, so confirm it in the service data before you start pulling coils.

Can I keep driving with P0308?

Not for long. A steady light allows a careful drive to a workshop, but a flashing light means the catalytic converter is receiving unburned fuel and can overheat. Continuing to drive also risks fuel washing oil off the cylinder wall of the misfiring cylinder.

Are the rear cylinders more likely to misfire?

They can be. Rear cylinders sit closest to the bulkhead, where heat builds up, so coils and plug boots there work in harsher conditions, and rear plug wells are harder to see into, so oil or water collecting there goes unnoticed for longer. A front cylinder can misfire just as well, so always confirm with the coil swap.

I have both P0307 and P0308. Is that one fault or two?

Look for what the two cylinders share. On a Ford-numbered V8 they sit side by side at the rear of the same bank, so a shared harness, an intake leak on that side or water in the rear plug wells is worth checking first. On a GM V8 they sit on opposite banks, so a fuel, air or engine-wide cause is more likely than two coils failing at once.

How much does a P0308 repair cost?

A single coil or a set of spark plugs usually costs about €70 to €330 fitted at an independent workshop, more where the rear coils sit under intake parts. Injector work and intake gasket repairs cost more, and internal engine work is the expensive end, which is why the cheap swap tests come first.

P0308: Cylinder 8 Misfire Detected

Quick Answer

Not safe to drive

P0308 means the engine computer has detected repeated misfires on cylinder 8. Only engines with eight or more cylinders can set it, so it belongs to V8s, V10s and V12s. Cylinder 8 usually sits at the back of the engine next to the bulkhead, and the most common causes are the spark plug or ignition coil on that cylinder, then the injector, an intake leak or low compression.

Severity: High · Misfire
Estimated repair cost: From €55 to €2700+, varies by vehicle

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What does P0308 mean?

P0308 is a misfire-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P0308 and illuminates the check engine light.

What are the symptoms of P0308?

If your vehicle has triggered P0308, you may notice one or more of these symptoms:

Check engine light on, or flashing while the misfire is active
Shaking or rough running at idle
Loss of power and stumbling under load, for example uphill or when towing
Fuel consumption higher than usual
Fuel smell from the exhaust or occasional popping
Harder starting or a rough first minute after a cold start

What causes P0308?

Here are the most common causes of P0308:

Failed ignition coil on cylinder 8
: high
Worn, cracked or fouled spark plug on cylinder 8
: high
Clogged, leaking or electrically failed fuel injector on cylinder 8
: medium
Intake leak at the rear of the manifold near cylinder 8
: medium
Water or oil in the cylinder 8 plug well shorting the coil boot
: medium
Low compression on cylinder 8 from a burnt valve, worn rings or a failed lifter
: low

Is it safe to drive with P0308?

No - address this immediately. A steady check engine light lets you drive carefully to a workshop, but a flashing light means cylinder 8 is sending unburned fuel into the catalytic converter. If it flashes, pull over when safe and have the car recovered.

How do you diagnose P0308?

Follow these steps to pinpoint the root cause of P0308:

Read all stored and pending codes and the freeze frame. Check the engine speed, load and temperature when the misfire was logged: cold-only misfires often point to fuel or a cracked plug, hot-only misfires more often to a coil breaking down with heat.
Locate cylinder 8 using the service data for your engine. On GM V8s it is the rearmost cylinder on the right bank, on Ford V8s the rearmost cylinder on the left bank; European makers use their own numbering.
Remove the cylinder 8 coil and look into the plug well for oil or water, then pull the plug and check its gap, electrode wear and insulator.
Swap the cylinder 8 coil with a neighbouring cylinder, clear the codes and drive. If the misfire follows the coil, the coil is faulty.
If the misfire stays on cylinder 8, test the injector: check its connector, listen for it on a port-injected engine, or have a workshop test a direct injector.
Look at the long-term fuel trim on the bank containing cylinder 8. A lean trim on that side only suggests an intake leak near the rear of the manifold; confirm it with a smoke test.
Run a compression test on cylinder 8 and compare it with the others, followed by a leak-down test if it reads low, to separate valve trouble from worn rings.
After the repair, clear the codes and complete a drive with idle, steady cruising and acceleration to confirm the misfire is gone.

How much does P0308 cost to fix?

Repair costs for P0308 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Replace spark plug on cylinder 8 (on a V8 usually the full set of eight)	€15–€120	€40–€200	€55–€320	Moderate
Replace ignition coil on cylinder 8	€40–€180	€30–€150	€70–€330	Easy
Clean or replace fuel injector on cylinder 8	€60–€250	€80–€150	€140–€400	Professional
Intake manifold gasket or vacuum hose repair	€40–€150	€150–€400	€190–€550	Moderate
Cylinder head, valve or lifter work after a failed compression or leak-down test	€300–€1200	€400–€1500	€700–€2700	Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

Full repair guides

P0308 on specific vehicles

P0308 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0308 on Chevrolet

Chevrolet Silverado 1500 5.3 V8 (Gen IV, AFM)

See Chevrolet-specific causes & cost

P0308 on BMW

BMW 5 Series 545i / 550i (N62 V8) · BMW X5 xDrive50i (N63 twin-turbo V8)

See BMW-specific causes & cost

P0308 on Audi

Audi S5 Coupe (B8, 4.2 FSI V8)

See Audi-specific causes & cost

P0308 on Mercedes-Benz

Mercedes-Benz S500 / S550 (W221, M273 V8)

See Mercedes-Benz-specific causes & cost

These codes are often seen alongside P0308 or indicate related issues:

Common questions about P0308

Where is cylinder 8 located?: On GM V8s (Chevrolet, GMC), even-numbered cylinders sit on the right bank, so cylinder 8 is the rearmost cylinder on that side, next to the bulkhead. On Ford V8s the left bank carries cylinders 5 to 8, so cylinder 8 is the rearmost on the left. European V8s differ between makers, so confirm it in the service data before you start pulling coils.
Can I keep driving with P0308?: Not for long. A steady light allows a careful drive to a workshop, but a flashing light means the catalytic converter is receiving unburned fuel and can overheat. Continuing to drive also risks fuel washing oil off the cylinder wall of the misfiring cylinder.
Are the rear cylinders more likely to misfire?: They can be. Rear cylinders sit closest to the bulkhead, where heat builds up, so coils and plug boots there work in harsher conditions, and rear plug wells are harder to see into, so oil or water collecting there goes unnoticed for longer. A front cylinder can misfire just as well, so always confirm with the coil swap.
I have both P0307 and P0308. Is that one fault or two?: Look for what the two cylinders share. On a Ford-numbered V8 they sit side by side at the rear of the same bank, so a shared harness, an intake leak on that side or water in the rear plug wells is worth checking first. On a GM V8 they sit on opposite banks, so a fuel, air or engine-wide cause is more likely than two coils failing at once.
How much does a P0308 repair cost?: A single coil or a set of spark plugs usually costs about €70 to €330 fitted at an independent workshop, more where the rear coils sit under intake parts. Injector work and intake gasket repairs cost more, and internal engine work is the expensive end, which is why the cheap swap tests come first.

Read our detailed guides

Scan your car with Skanyx to diagnose P0308

Your car logged P0308. Skanyx reads it on a standard OBD2 adapter (Bluetooth LE on iPhone), tells you whether it is safe to keep driving, and shows the €55-€2700 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.