Cylinder 6 Misfire Detected
In short
P0306 means your engine's computer detected that cylinder 6 is misfiring — it isn't burning its air/fuel mixture properly and reliably. The single most common real-world cause is a worn spark plug or a failed ignition coil on that cylinder. You'll often feel a rough idle, hesitation, or a flashing check-engine light, and the fix is usually inexpensive if caught early.
Is it safe to drive with P0306?
It is generally safe to drive a short distance, but a misfire dumps unburned fuel into the exhaust and can overheat and destroy the catalytic converter. If the check-engine light is flashing, that signals an active misfire causing converter damage — reduce load, avoid hard acceleration, and fix it as soon as possible.
Symptoms
- Rough or shaky idle, especially when stopped
- Engine hesitation or stumble under acceleration
- Noticeable loss of power and reduced fuel economy
- Check-engine light on, or flashing during active misfire
- Unusual exhaust smell (raw fuel) or occasional popping from the tailpipe
- Vibration felt through the steering wheel or seat at idle
Common causes (most → least likely)
How to diagnose it (before buying parts)
- 1 Scan all stored codes and freeze-frame data; note whether other misfire codes (P0300–P0312) are present and the conditions when P0306 set.
- 2 Check live data for cylinder 6 misfire counts and compare against the other cylinders to confirm it's isolated to cylinder 6.
- 3 Visually inspect the cylinder 6 coil, boot, connector, and wiring for cracks, oil, corrosion, or looseness.
- 4 Swap the cylinder 6 coil (and/or spark plug) with a known-good neighboring cylinder, clear codes, and drive — if the misfire follows the part to the new cylinder, that part is the fault.
- 5 If the misfire stays on cylinder 6, test fuel injector operation and perform a compression or cylinder leak-down test to rule out a mechanical problem before buying parts.
Repair options & cost
By manufacturer
V6 engines (e.g. the 2GR family) are known for individual coil-on-plug failures that throw single-cylinder misfire codes; replacing the affected coil and plug usually resolves it.
V6 J-series engines commonly develop cylinder misfires from aged iridium plugs and coils; on VCM-equipped models, rear-bank cylinders can foul faster, so check plug condition first.
On V6 and V8 coil-on-plug engines, cracked coil boots and worn plugs are frequent single-cylinder misfire causes; inspect the boot for arcing tracks before condemning the coil.
VQ-series V6 engines are prone to ignition coil failures that set isolated misfire codes like P0306; coils often fail one at a time as they age.
Frequently asked questions
Can I drive with a P0306 code?
For a short distance, usually yes, but you should fix it quickly. A persistent misfire pumps unburned fuel into the exhaust and can overheat and ruin the catalytic converter — a far more expensive repair. If the check-engine light is flashing, drive as little as possible and avoid heavy acceleration.
How much does it cost to fix a P0306 misfire?
Most P0306 repairs land between 100 and 400 dollars when the cause is a spark plug or ignition coil. If a fuel injector is to blame, expect roughly 200 to 550 dollars at a shop. Mechanical causes like low compression are far more expensive, often 1,000 dollars or more.
Where is cylinder 6 located?
Cylinder location depends on the engine's firing layout and varies by manufacturer, so check a cylinder-numbering diagram for your specific engine. On many V6 and V8 engines, cylinder 6 is on the rear bank. Always confirm with a service manual before swapping parts.
Will a misfire on one cylinder damage my engine?
A single-cylinder misfire usually won't immediately destroy the engine, but it can quickly damage the catalytic converter and, over time, wash oil off the cylinder walls. Repeated or prolonged misfires can also stress engine mounts and other components, so prompt repair is the cheaper path.