P0306 means the ECU has detected repeated misfires on cylinder 6. Because cylinder 6 only exists on engines with six or more cylinders, this code is found exclusively on inline-6, V6, V8, and larger configurations. Common culprits are an ignition coil or spark plug specific to cylinder 6, a clogged injector, or in rarer cases compression loss in that cylinder.
Estimated repair costFrom €38 to €2300+, varies by vehicle
What does P0306 mean?
P0306 means the ECU has detected repeated misfires on cylinder 6. Because cylinder 6 only exists on engines with six or more cylinders, this code is found exclusively on inline-6, V6, V8, and larger configurations. Common culprits are an ignition coil or spark plug specific to cylinder 6, a clogged injector, or in rarer cases compression loss in that cylinder.
P0306 is a misfire-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P0306 and illuminates the check engine light.
What are the symptoms of P0306?
If your vehicle has triggered P0306, you may notice one or more of these symptoms:
Check engine light on or flashing
Noticeable rough idle and vibration through the seats
Loss of power, especially under load
Increased fuel consumption
Possible fuel smell from the exhaust
What causes P0306?
Here are the most common causes of P0306, ranked by how likely they are to be the culprit:
highFailed ignition coil on cylinder 6
highWorn or fouled spark plug on cylinder 6
mediumClogged or leaking fuel injector on cylinder 6
mediumVacuum leak near cylinder 6 intake runner
lowLow compression on cylinder 6 (valve or ring wear)
Is it safe to drive with P0306?
No - address this immediately. A persistent single-cylinder misfire dumps unburned fuel into the catalytic converter, which can overheat and fail. If the check engine light is flashing, stop driving and have the vehicle recovered to a workshop.
How do you diagnose P0306?
Follow these steps to pinpoint the root cause of P0306:
Read freeze-frame data and look at RPM, load, and coolant temperature when the misfire was logged. Cold-only misfires often point to fuel; hot-only misfires often point to ignition coils heat-soaking
Swap the ignition coil from cylinder 6 with a coil from a healthy cylinder. Clear codes and drive. If the misfire follows the coil, replace it
Remove the cylinder 6 spark plug and inspect for wear, fuel fouling, oil deposits, or a cracked porcelain. Replace any plug that looks suspect
Listen to the cylinder 6 injector with a stethoscope. A weak or absent click points to electrical or mechanical injector failure
Perform a compression test on cylinder 6 and compare to the others. A difference of more than 10% indicates an internal engine issue requiring deeper inspection
How much does P0306 cost to fix?
Repair costs for P0306 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 (cylinder 6)
€8–€30
€30–€120
€38–€150
Easy
Replace ignition coil (cylinder 6)
€40–€180
€30–€150
€70–€330
Easy
Clean or replace fuel injector (cylinder 6)
€60–€250
€100–€350
€160–€600
Professional
Cylinder head or valve repair
€200–€800
€400–€1500
€600–€2300
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0306 on specific vehicles
P0306 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
P0306 on BMW 3 Series
BMW 3 Series • 2005-2024
The E90 330i with the N52 inline-six is famous for failing the cylinder 6 ignition coil first because of heat soak at the rear of the engine. BMW recommends replacing coils and plugs as a set at around 80,000 km. P0306 is one of the most common codes flagged on N52 in independent specialist shops.
What causes P0306 on a BMW 3 Series?
BMW 3 SeriesCylinder 6 ignition coil heat-soak failure on N52 (rear position)
BMW 3 SeriesCylinder 6 injector wear on N54 twin-turbo
P0306 repair cost for BMW 3 Series
Estimated costs for BMW 3 Series ownersadjusted higher than average due to BMW-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace spark plug (cylinder 6)
€11–€42
€42–€168
€53–€210
Easy
Replace ignition coil (cylinder 6)
€56–€252
€42–€210
€98–€462
Easy
Clean or replace fuel injector (cylinder 6)
€84–€350
€140–€490
€224–€840
Professional
Cylinder head or valve repair
€280–€1120
€560–€2100
€840–€3220
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0306 on Mercedes C-Class
Mercedes-Benz C-Class • 2008-2018
W204 C350 with the M272 V6 commonly logs P0306 from a worn cylinder 6 ignition coil and a small vacuum leak at the rear of the intake manifold. The intake plenum has known cracking issues near the Bank 2 rear runner, which affects cylinder 6 most.
What causes P0306 on a Mercedes C-Class?
Mercedes C-ClassCylinder 6 coil wear on M272 V6
Mercedes C-ClassIntake plenum crack near Bank 2 rear runner
P0306 repair cost for Mercedes C-Class
Estimated costs for Mercedes C-Class ownersadjusted higher than average due to Mercedes-Benz-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace spark plug (cylinder 6)
€11–€41
€41–€162
€51–€203
Easy
Replace ignition coil (cylinder 6)
€54–€243
€41–€203
€95–€446
Easy
Clean or replace fuel injector (cylinder 6)
€81–€338
€135–€473
€216–€810
Professional
Cylinder head or valve repair
€270–€1080
€540–€2025
€810–€3105
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0306 on Audi A6
Audi A6 • 2011-2024
C7 A6 with the 3.0 TFSI supercharged V6 sometimes triggers P0306 from cylinder 6 injector wear or a leaking supercharger coolant pipe in close proximity to the rear cylinders. The supercharger sits in the valley, so any leak above it tends to affect cylinders 5 and 6 first.
What causes P0306 on a Audi A6?
Audi A6Cylinder 6 injector wear on 3.0 TFSI
Audi A6Supercharger coolant pipe leak biasing toward rear cylinders
P0306 repair cost for Audi A6
Estimated costs for Audi A6 ownersadjusted higher than average due to Audi-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace spark plug (cylinder 6)
€10–€39
€39–€156
€49–€195
Easy
Replace ignition coil (cylinder 6)
€52–€234
€39–€195
€91–€429
Easy
Clean or replace fuel injector (cylinder 6)
€78–€325
€130–€455
€208–€780
Professional
Cylinder head or valve repair
€260–€1040
€520–€1950
€780–€2990
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0306 on Toyota Camry
Toyota Camry • 2007-2018
Camry V6 with the 2GR-FE typically logs P0306 from a worn cylinder 6 coil or a clogged injector. The rear bank is harder to reach because the intake plenum and wiper cowl block access, so independent shops charge a bit more for V6 misfires than for the four-cylinder Camry.
What causes P0306 on a Toyota Camry?
Toyota CamryCylinder 6 ignition coil failure on 2GR-FE
Toyota CamryCylinder 6 injector clog from poor fuel quality
Related diagnostic codes
These codes are often seen alongside P0306 or indicate related issues:
A single-cylinder misfire code is the ECU telling you that one specific cylinder is contributing to crankshaft acceleration less than its neighbours. The cause is almost always something localised to that cylinder: its coil, plug, injector, or valves, rather than a problem that would affect the whole engine.
Can I drive with cylinder 6 misfiring?
Only as far as the nearest workshop, and ideally with a tow if the check engine light is flashing. A persistent misfire pumps unburned fuel into the catalytic converter, which can overheat and fail. Catalyst replacement is usually the most expensive part of fixing an ignored misfire.
Where is cylinder 6 on a V6 or inline-6?
On most inline-6 engines (BMW N52, N54, N55, B58), cylinder 6 is at the rear, closest to the firewall. On V6 engines the location depends on manufacturer numbering: on BMW V6 it is the rearmost cylinder on Bank 2, on most Toyota V6 it is the rearmost cylinder on Bank 1. Check a wiring diagram for your engine.
Why does the BMW N52 fail cylinder 6 first?
On the N52 inline-six, cylinder 6 sits at the back near the firewall where heat soak is highest. The ignition coil over cylinder 6 routinely fails before the others. Mechanics replace it as a pair (cylinders 5 and 6) when they see the first failure to avoid a repeat visit.
