P0306 Code? Run the VIN Before You Pay for Parts

A P0306 code is the OBD-II diagnostic trouble code (DTC) for cylinder 6 misfire detected: the engine computer counted too many strokes on which cylinder 6 failed to fire. It lights the check engine light, which flashes when the misfire is bad enough to harm the catalytic converter.

Toyota's bulletin writes it as P030600, and owners' complaint forms also show it as PO306 with a letter O. Only an engine with six or more cylinders has a cylinder 6, so the code comes from a V6, a V8 or an inline six.

Owners filed 71 federal complaints naming P0306 on 2010 to 2025 models, and Honda leads them by make, with 12. In 37 of them, cylinder 6 was the only cylinder code stored.

What does P0306 mean?

P0306 means cylinder 6 alone misfired often enough to raise emissions, or often enough to threaten the catalytic converter. The P0300 page explains how the computer counts misfires for every one of these codes.

A lone P0306 means the computer could blame a single cylinder. Next to P0300, the random misfire code, the miss may be spreading, and 32 of the 71 complaints carry both.

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Can you drive with a P0306 code?

Yes, while the light stays steady, as long as you drive gently and get to a shop soon. A flashing light means easing off and getting it serviced right away, and coolant that keeps disappearing means the car stays parked.

A steady light gives you time to book the repair. These three signs change the answer:

• The light flashes. The blink means the same on any code, as flashing check engine light explains, and bad catalytic converter symptoms shows where an ignored misfire ends up.
• The coolant keeps dropping. Coolant in a cylinder can overheat the engine: a 2019 Pacifica owner's engine lost its coolant into cylinder 6 and overheated at freeway speed.
• It shakes hard, stalls or loses power. Owners describe losing power while passing at highway speed, and a 2014 F-150 stalled as its driver pulled alongside another car.

What the manuals say 2 manuals

• 2012 Ford F-150, page 13. Flashing warns of a misfire that could damage the catalytic converter; Ford says to drive in a moderate fashion and have it serviced immediately.
• 2020 Chevrolet Silverado, pages 135–136. GM says to reduce speed while it flashes, avoid hard acceleration and uphill grades, and park, switch off and wait at least 10 seconds if it keeps flashing.

Both manuals' wording, side by side, is on the P0300 page. It also covers why some misfires flash the lamp and others leave it steady.

Will a P0306 code go away on its own?

The light can go out while cylinder 6 still misses. California's OBD-II rule lets the light go out after three trips in a row under similar driving conditions with no misfire over the limit, and a miss that returns lights it again.

The stored code outlasts the light: the rule lets the computer erase it after 40 warm-up cycles without the fault, each a drive that warms the coolant by at least 40°F to at least 160°F. A scan tool clears the stored code, not the cause.

What causes a cylinder 6 misfire?

A part only cylinder 6 uses, its plug, coil or injector, or damage inside the cylinder: coolant, a leaking head or worn valvetrain parts. Carmakers' documents add wiring at one connector and engine software.

The code names the cylinder, not the part, and a second code stored with it can change which cause comes first. Here's each cause with the test that comes next:

Here's what owners name in their complaints, which isn't a diagnosis:

The sections below take each cause in the table's order, starting with the three parts only cylinder 6 uses. The last five cover the cylinder itself, the wiring and the engine's software.

1. Spark plug

The plug fires the mixture in cylinder 6, and a worn, cracked or fouled one misfires that cylinder alone. Owners name spark plugs in 14 of the 71 complaints, level with the valvetrain.

Chrysler has also dealt with plugs by the batch, cracked ones on its 3.6L V6 and badly gapped ones on a supercharged V8. Both bulletins are in the bulletin list further down.

2. Ignition coil

The coil turns the battery's 12 volts into the high voltage plug 6 needs, and on coil-on-plug engines it sits on that plug alone. Five of the 71 complaints name a coil, fewer than name the plug or the valvetrain.

A coil costs more than a plug at the counter, $15 to $85 against $2 to $15, parts only. The swap section shows how to prove it before you buy one.

3. Fuel injector

Injector 6 sprays the fuel for that cylinder: clogged, it starves the mixture, and leaking, it floods it. Ten of the 71 complaints name an injector, and 3 of them are 2016 to 2019 Hondas.

Honda extended the injector warranty on some Pilot, Ridgeline and Odyssey models, free only if the dealer finds the codes relate to the injectors or, on some earlier models, the engine software. FCA has also replaced one high-flow batch of injectors on a V8, and both documents are in the bulletin list.

4. Coolant in the cylinder

The head gasket keeps coolant out of the cylinders where the head meets the block, and a damaged cylinder wall can let it in too. Coolant comes up in 6 of the 71 complaints, while the head gasket comes up in 3, each of those on a Chrysler.

A cooling-system pressure test proves the leak, not the code. Two owners describe what it looked like:

5. Leaking cylinder head

A low compression or leakage reading on cylinder 6 can point at the head, and a leakage test is how a shop finds it. On Chrysler's early 3.6L V6, the bulletin for P0306 sends the dealer to that test on the even cylinders first, and 25% or more on cylinder 2, 4 or 6 means a new left head.

Nine of the 71 complaints are on models and years that bulletin lists, though it covers only the 3.6L, and four of them are Wranglers. One 2013 Wrangler owner's report reads low compression detected in cylinder 6.

6. Worn valvetrain

Cam lobes, lifters and rockers open the valves, so a flat lobe or a collapsed lifter leaves cylinder 6 short of air. Cam, lifter or rocker parts come up in 14 complaints, and 5 of them are on GMC trucks and SUVs.

GM replaces lifters on some 5.3L and 6.2L trucks and SUVs from one build window, and Chrysler describes worn intake cam lobes on its 3.6L V6. A 2021 Tahoe owner reports an AFM lifter collapse on Cylinder 6.

7. Wiring

The harness carries the firing signal to coil 6 and the pulse to injector 6. FCA recorded a low-mileage 3.6L Challenger whose P0306 came from damaged terminals at one engine-harness connector.

Its record says to rule out a software update first, then inspect that circuit's terminals and repair them with a kit. Owners name wiring or a connector in 4 of the 71 complaints, and a vacuum leak near cylinder 6 is worth a look, though no carmaker document we read ties one to P0306.

8. Engine software

The engine computer times each spark and each injector pulse, so its programming can set a misfire with no failed part. The fix is then a reprogram at the dealer, found by VIN.

Toyota's bulletin lists only cylinders 5 and 6 among its cylinder codes, on two V6 models at full throttle, and Nissan and Ford have reprogrammed engines for misfire codes that include P0306. The bulletin list names the cars.

How do you tell the coil from the cylinder?

Move coil 6 to another cylinder, clear the code and drive. If the misfire follows the coil, replace it, and if P0306 returns, plug 6 and the cylinder are next.

Ford and GM both write that swap into their own diagnosis for some engines. A trade magazine reports that some carmakers advise against swapping coils on certain engines, so check the service information first, and the P0300 page covers the full misfire diagnosis.

If the code stays on cylinder 6 after the swap, the carmakers test the cylinder next:

• GM: relative compression. Fail it and the shop moves on to a leakage test and the valvetrain; pass it and the fault is back in ignition or fuel.
• Chrysler 3.6L: leakage. Its head bulletin runs a cylinder leakage test on cylinders 2, 4 and 6 before any part is replaced.

Coil swap in the documents 2 docs

• Ford F-150 3.5L EcoBoost, 2021–22. Ford moves the coil from the misfiring cylinder to a good one and replaces it only when the misfire moves with it. Special service message 50412.
• GM direct-injection engines, 2012–14. For a weak cylinder, GM swaps both the coil and the plug with another cylinder and looks the plug over. Bulletin PIP5062C.

Where is cylinder 6?

Engine makers number cylinders their own way, and only engines with six or more cylinders have a cylinder 6. Counting from the front can point at the wrong one, as the P0300 page explains, and the map in the first section cuts open cylinder 6 on a generic V6 to show its parts, not where it sits on yours.

On Chrysler's early 3.6L V6, the bulletin for this code leak-tests cylinders 2, 4 and 6 and then replaces the left, front head, which by our reading puts cylinder 6 on that head. The bulletin never says which bank cylinder 6 sits on, so have the shop point to coil 6 before anything comes off.

What the documents say 1 doc

• 2011–13 Chrysler 3.6L V6. Cylinders 2, 4 and 6 are leak-tested, and the fix is a new left cylinder head, booked as the left, front side; the bulletin doesn't say which bank holds cylinder 6. Bulletin 09-002-14 Rev. B.

How do you fix a P0306 code?

By proving the failed part before paying for one, starting with the checks that cost nothing. To fix a P0306 code, work through the 7 steps below, in order:

1. Write down every code and the freeze frame. The freeze frame is the engine data the computer saves the moment a code sets. P0305, P0304 or P0300 beside P0306 changes where to look.
2. Check the coolant level. If it keeps dropping with no coolant leak in sight, the coolant may be going into a cylinder. Park the car and ask for a cooling-system pressure test first.
3. Run the VIN. A dealer finds bulletins, warranty extensions and software updates by VIN, including Honda's injector extension and Chrysler's 3.6L head bulletin. Our free VIN checker shows open recalls and owner complaints first.
4. Move coil 6 to another cylinder. Clear the code and drive; if the misfire moves with the coil, replace the coil, and if P0306 comes back, go to the plug. Check the service information first, or leave it to the shop.
5. Pull plug 6 and look at it. Check the gap and look for cracks. A plug wet with coolant points past the plug, into the cylinder.
6. Have injector 6 checked at a shop. On a 2016 to 2019 Pilot, Ridgeline or Odyssey, ask whether Honda's extension applies before paying. On a 2021 Challenger, Charger, Durango, Grand Cherokee or Wrangler with the 6.4L V8, the VIN check covers FCA's high-flow batch.
7. Then test compression and leakage on cylinder 6. A low reading points at a head gasket, a valve, the head or the valvetrain, and a pass sends the shop back to ignition and fuel. On a 2011 to 2013 Chrysler 3.6L, 25% leakage or more on cylinder 6 is the bulletin's line for a new left head.

You can move coil 6 and read plug 6 at home, while injector, compression and leakage testing need a shop. If a quote calls for a new head or engine without a leakage result, ask for that test first, as GM and Chrysler do; reading a repair estimate lists other questions.

After the repair, clear the code and drive to confirm the light stays off. Honda warns its owners that with the light on, a car may fail a state or local emissions inspection.

How much does it cost to fix P0306?

Every part in the box costs under $125 at the counter, so the cause and the labor decide the bill. The box prices them on the F-150, the Silverado and the Highlander.

The list below gives US shop averages for the whole job, parts and labor, from a national repair-cost index for 2026, not counter prices. Compare a shop's quote with these, and the parts-only prices in the box with what the part alone costs.

• Spark plugs. $299 for the job, parts and labor, or $480 with coils. US average from a national repair-cost index for 2026.
• Ignition coil. $256 for the job, parts and labor. US average, same index.
• Fuel injector. $572 for the job, parts and labor. US average, same index.

A fault inside the cylinder costs far more than anything in the box, which is why the VIN check comes before parts. Chrysler's 3.6L head bulletin books 8.2 to 10.2 hours for one head before AWD add-ons, and head gasket replacement cost covers that kind of job out of warranty.

Dealer labor times 3 jobs

• 2012–13 Jeep Wrangler 3.6L, replace the left cylinder head. 9.0 hours, leakage test included. Bulletin 09-002-14 Rev. B.
• 2018 Toyota Camry V6, engine computer reprogram. 0.7 hours, covered by Toyota's federal emission warranty. Bulletin T-SB-0071-18.
• 2021 Ford Transit 3.5L EcoBoost, engine computer reprogram. 0.4 hours. TSB 21-2225.

Of the 17 bulletins we read that name P0306, one names it alone, and who pays differs from one to the next. Some are warranty repairs, Honda extended its injector coverage, Toyota's sits under its emission warranty, and FCA's cam bulletin and wiring record are information only.

Chrysler, Dodge, Jeep and Ram vehicles make up 20 of the 71 complaints. On a Chrysler 3.6L or a 2016–19 Pilot, Ridgeline or Odyssey, run the VIN before you pay for a plug, a coil or an injector, and check what Chrysler and Honda say for every bulletin.

Which cars report a P0306 code most?

Any engine with six or more cylinders can set the P0306 engine code, and owners' federal complaints name some models more than others. The Ford F-150 leads with 8 of the 71 and the Honda Pilot has 7, ahead of the Jeep Wrangler with 6.

All 7 Pilot complaints are 2016 to 2019 models, the years Honda's injector extension covers, and 2 of them name the injectors. After the Wrangler come the Chrysler Pacifica with 5, the Honda Odyssey and Kia Sedona with 4 each, and the GMC Sierra 1500 (the Chevy Silverado's twin), Dodge Grand Caravan and Kia Sorento with 3 each.

These counts show who reported, not how often a model fails. Big sellers collect more complaints of every kind.

Which codes come with P0306?

A second code beside P0306 tells you whether cylinder 6 is the whole story. Owners' complaints and carmakers' bulletins list these codes with it:

Codes that come with P0306 3 pairings

• P0300. Listed with P0306 in 32 of the 71 complaints; the P0300 page covers the random misfire code.
• P0305. Listed with P0306 in 13 of the 71 complaints; Toyota's high-load bulletin names only these two cylinder codes.
• P0302 and P0304. On a 2011 to 2013 Chrysler 3.6L, the even cylinders together match its head bulletin, which lists P0300, P0302, P0304 and P0306.

OBD-II · Misfire codes

Other OBD-II misfire codes and what each one means

1. P0300 random misfire

2. P0301 cylinder 1

3. P0302 cylinder 2

4. P0303 cylinder 3

5. P0304 cylinder 4

6. P0305 cylinder 5

What are the symptoms of a P0306 code?

A check engine light, steady or flashing, with shaking, lost power, stalling or a rough idle. Owners name lost power and shaking most, in 16 of the 71 complaints each.

A flashing light means the misfire could overheat the catalytic converter, and the other signs show how badly cylinder 6 is missing. Here's what each one tells you:

• Lost power or hesitation. Cylinder 6 has stopped pulling its weight; jerking when accelerating covers the feel and its other causes.
• Shaking or vibration. The engine runs unevenly with one cylinder dead.
• A flashing check engine light. The warning that the misfire could overheat the catalytic converter.
• Stalling or a rough idle. The miss shows even at a standstill, or stops the engine.

Common questions

Asked most often

What is the most common cause of a P0306 code?

Complaints name parts, not confirmed causes: in the 71 that name P0306, owners name the spark plug and the cam, lifter or rocker in 14 each, and an injector in 10. On some 2016–19 Pilot, Ridgeline and Odyssey models, Honda extended the injector warranty.

Can a bad spark plug cause P0306?

Yes: owners name the plug in 14 of the 71 complaints, and Chrysler replaced a batch of cracked 3.6L plugs that set misfire codes including P0306. Pull plug 6 after the coil swap and check it.

Is P0306 covered by warranty?

Sometimes: Chrysler's 3.6L head bulletin carries extended coverage, and some of its plug and injector bulletins are paid under normal warranty. Honda covers the injectors on some 2016–19 Pilot, Ridgeline and Odyssey models to 10 years or 150,000 miles, free only if the dealer finds the codes relate to the injectors or, on some earlier models, the engine software.

Can a bad O2 sensor cause a P0306 code?

Not in the documents we read: no carmaker bulletin we read ties an oxygen sensor to P0306. On some 2016–19 Pilot, Ridgeline and Odyssey models, catalyst codes P0420 and P0430 come with P0306 under the same injector extension.

Prices are ranges compiled in September and October 2026 for the US market and vary by region, engine and shop rate. Prices from $10 up are rounded to the nearest dollar, so $14.13 reads as $14 and $14.52 as $15. Below $10 they're exact. This article is general information, not advice about your specific vehicle. See the disclaimer.