P0306: Cylinder 6 Misfire Detected
Key takeaways
- P0306 means the engine computer counted too many misfires on cylinder 6, so it only appears on engines with six or more cylinders.
- If the check engine light flashes, stop driving: the misfire is sending unburned fuel into the catalytic converter.
- Most P0306 fixes are an ignition coil ($120–$300) or a set of spark plugs ($250–$600 on a V6 or V8).
- 91 complaints filed with NHTSA mention P0306; the Jeep Wrangler, Ford F-150 and Honda Pilot lead with 7 each.
- 233 manufacturer bulletins name P0306, many of them engine-computer software updates or cold-start misfire procedures.
What P0306 means
Cylinder 6 is misfiring, meaning it isn’t burning its fuel properly on every stroke. Scanners call it Cylinder 6 Misfire Detected. The engine computer times each firing pulse off the crankshaft sensor; when cylinder 6 fails to speed the crank up the way the others do, often enough to cross the limit, it sets P0306.
P0306 only exists on engines with at least six cylinders: V6, inline six or V8. A four- or five-cylinder car cannot set it, so a P0306 on one of those means the reader is set to the wrong vehicle.
Is it safe to drive?
Short trips only, and stop if the light is flashing. With a steady light and a slight shake, drive gently to a shop and avoid hard acceleration and towing. A flashing check engine light means the misfire is heavy and unburned fuel is heating up the catalytic converter, which can overheat and fail. Pull over when it is safe. Do the same if the engine shakes hard, loses power or you smell fuel.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Failed ignition coil | Swap coil 6 with a neighbor on the same bank; the code follows the coil | $120–$300 per coil |
| Worn or fouled spark plug | High mileage, wide gap, oil or carbon on the tip, cracked porcelain | $150–$350 a set (4-cyl), $250–$600 (V6/V8) |
| Clogged or leaking fuel injector | Coil and plug are good; injector test or stethoscope shows cylinder 6 is weak or silent | $250–$600 per injector |
| Vacuum leak near cylinder 6 | Lean code such as P0171 alongside; smoke test finds the leak | $50–$400 |
| Software fault | Matching bulletin for your engine; common on newer trucks and SUVs | $100–$200, often $0 under warranty |
| Low compression (valve, ring, lifter, head gasket) | Compression or leak-down test on cylinder 6 reads low | $1,500–$4,500 |
What to check first
- Save the freeze-frame data before clearing anything. Cold, idle or load conditions point to different causes.
- Look for other misfire codes. One cylinder points to that cylinder’s parts; several, with P0300, point to fuel, vacuum or timing.
- Swap the coil with a neighboring cylinder on the same bank, clear, and drive. Code moves: coil. Code stays: plug next.
- Pull and read the plug. Check for oil in the plug tube, a torn boot, or a worn electrode.
- Test injector and compression only after coil and plug check out.
On transverse V6 engines in minivans and crossovers, the rear bank plugs often need the intake plenum removed, so the labor on a cylinder 6 job can vary a lot by car.
Across the bulletins, the pattern is software and cold starts. Stellantis (Ram 1500 and 3500, Jeep Wagoneer) and Ford (2024 F-150 PowerBoost, 2021–2022 Mustang 5.0) issued engine-computer updates for misfire codes including P0306. Nissan and Infiniti have cold-start misfire bulletins for the 2022 Frontier, Pathfinder and QX60, and Dodge has a spark plug re-gap bulletin for the Challenger.
What it costs
The cheap outcome is one coil, $120–$300. The common outcome is a coil with fresh plugs, more on engines where the rear plugs are buried. The expensive outcome is low compression from a valve or head gasket, $1,500–$4,500. An hour of diagnosis, usually $100–$180, costs less than guessing through plugs, coils and injectors. You can also ask our AI mechanic to walk through your freeze-frame data first.
Related codes
P0306 often shows up with P0300 and with a neighboring cylinder such as P0305 or P0304. A lean code with it means look for a vacuum leak first. If the light is flashing now, see check engine light flashing; for a shaky idle, see rough idle.
What owners report to NHTSA
91 complaints filed with NHTSA mention P0306, 70 of them since 2015, across 47 different models. The component owners most often filed it under: engine.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| JEEP WRANGLER | 7 | 2008, 2012, 2013, 2018 |
| FORD F-150 | 7 | 2012, 2013, 2014, 2016 |
| HONDA PILOT | 7 | 2016, 2017, 2019 |
| CHRYSLER PACIFICA | 5 | 2017, 2019 |
| TOYOTA 4RUNNER | 4 | 2004, 2005 |
| HONDA ODYSSEY | 4 | 2013, 2018, 2019 |
| KIA SEDONA | 4 | 2016, 2017 |
| LINCOLN LS | 3 | 2003, 2004, 2005 |
| GMC SIERRA 1500 | 3 | 2011, 2017, 2020 |
| DODGE GRAND CARAVAN | 3 | 2013, 2017 |
Manufacturer service bulletins that name P0306
233 technical service bulletins and manufacturer communications filed with NHTSA mention P0306, from 21 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- RAM 1500 (2025), bulletin 11008018: "Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): P01…
- FORD F-150 (2024), bulletin 11001886: Some 2024 F-150 vehicles built on or before 14-May-2024 equipped with a 3.5L PowerBoost may exhibit an illuminated MIL and set cylinder misfire DTCs P0300, P0316, P0301, P0302, P0302, P0304, P0305 and/or P0306. This may …
- JEEP WAGONEER (2023), bulletin 10239947: Flash: Powertrain Control Module (PCM) Updates Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following DTCs have been set:…
- DODGE CHALLENGER (2023), bulletin 11005019: Spark Plug Re-Gap to Resolve Misfire Symptoms Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): P0300…
- NISSAN FRONTIER (2022), bulletin 10207878: DTC P0300 AND/OR P0301(2/3/4/5/6) IS STORED DURING A COLD START IF YOU CONFIRM DTC P0300 and/or any of the following DTCs are stored in the ECM; P0301 P0302 P0303 P0304 P0305 P0306 AND The DTC only stores during a cold s…
- FORD GT (2017, 2018, 2019, 2020), bulletin 10209230: Some 2017-2022 Ford GT vehicles may exhibit a runs rough or hard start with or without an illuminated MIL with DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306 and/or P0316. Prior to performing any diagnostics, determ…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Can a 4-cylinder or 5-cylinder engine throw P0306?
No. Cylinder 6 only exists on six-cylinder and eight-cylinder engines. If a four- or five-cylinder shows P0306, the scanner has the wrong vehicle selected or is misreading the computer.
Can I drive with P0306?
Gently, for short trips to a shop, as long as the check engine light is steady and the engine isn't shaking badly. A flashing light means stop, because a heavy misfire can overheat the catalytic converter.
Where is cylinder 6?
It varies by engine. On an inline six it is usually the last cylinder in the row, but on V6 and V8 engines each manufacturer numbers the cylinders its own way. Look it up for your engine before pulling parts.
What if P0306 comes back after a new coil and plug?
Then the problem is fuel, air or compression on that cylinder. The next steps are an injector test, a smoke test for vacuum leaks, and a compression or leak-down test.
Why does P0306 only show up on cold starts?
A cylinder that misses only when cold can be a plug, an injector that drips, or a known software issue. Nissan and Infiniti have bulletins for misfire codes set during cold start on some 2022 models, so ask for a bulletin check.