P0301 Code: A Plug, a Coil, or Coolant on a Ford EcoBoost

OilAndMiles.com - A P0301 code, a cylinder 1 misfire, is one of the most searched OBD-II codes there is, and most answers to it stop at spark plugs and coils. That's right more often than not. But the federal complaint record tells a different story for one group of cars, and the manufacturer wrote it down several times.

What follows is the usual answer, whether to drive on it and what it costs, then the Ford, Honda and Toyota cases, and the order to check things in.

What does a P0301 code mean?

The engine computer counted too many misfires in cylinder 1. The code's full name is cylinder 1 misfire detected. The computer doesn't hear a missed firing; it watches how evenly the crankshaft speeds up, and a cylinder that doesn't fire leaves a gap in that rhythm.

How it counts, and why no fixed percentage trips it, is on the P0300 page. The last digit is the cylinder, so P0302 is cylinder 2, and the code reads the same on a European car, where the standard is called EOBD. The code is also often typed PO301 with a letter O, or P301, and neither is a code: the second character is a zero.

Which cylinder is number 1 depends on how the engine's maker numbers them, and on a V engine it isn't reliably the one at the front. Look it up for your engine before pulling anything.

What causes a cylinder 1 misfire?

Usually something that feeds that one cylinder: its spark plug, its coil or its injector. Past those is the cylinder itself, and two manufacturers have written that part down for specific engines:

• A spark plug. Worn or fouled, it can't light the mixture. It's the part owners name most, in 100 of the 332 federal complaints about this code.
• An ignition coil. Most modern engines have one per cylinder, and it can be tested by moving it, as in the steps below. Owners name it in 67.
• A fuel injector. No fuel, no fire. Named in 44.
• Coolant in the cylinder, on some Ford EcoBoost engines. Ford's own bulletins say coolant can get into the cylinder bore. The Ford sections further down are that case.
• Piston rings, on some older Hondas. Honda's bulletins say the rings can rotate and line up, which fouls the plug and sets the code. That case comes after the Ford one.

Use this image

Free to republish under CC BY 4.0: credit Oil & Miles and link to this page. The snippet does both.

Copy the snippet

Can you drive with a P0301 code?

Not far, and not at all if either of two things is happening:

• The light is flashing. That is the OBD-II regulation's signal that the misfire is heavy enough to damage the catalytic converter, which the flashing light page covers.
• The coolant level keeps falling. On the 1.5L and 2.0L Ford EcoBoost engines further down this page, coolant getting into the cylinder is a written cause. An engine using coolant is losing it from the system that stops it overheating, so a falling level is a reason to stop driving rather than to top it off and carry on.

In the federal record, 39 of the 332 filings describe the light flashing, and 43 describe the engine stalling.

What does it cost to fix a P0301 code?

Usually $256 to $572 at a shop, CarMD's US averages with labor for coils, plugs or injectors. The part itself is far less, and the box below prices it on the three models owners complain about most:

A misfire left alone is one of the things that kills a catalytic converter, which CarMD puts at $1,511. The Ford coolant case further down is a different order of money: owners' quotes for a new engine or block run from $5,676 to $16,170, which is why the coverage question comes before the repair.

Is P0301 a Ford problem?

In the federal complaint record, yes, and in the searching only partly. Of the 332 US complaints naming P0301 for model years 2010 to 2025, 140 are Ford or Lincoln. The badges people type with this code are closer to even: Toyota and Ford lead, with Honda and Chevy behind.

What sets the Ford filings apart is what's written beside the code: 117 of the 140 mention coolant.

P0316 appears with P0301 45 times, P0217 25 times, and P1285 and P1299 24 times each, which are the same codes Ford's bulletins list for coolant getting into the cylinder. None of those four appears beside P0301 on any make but Ford and Lincoln in the record.

Hyundai and Kia together account for 48 filings, spread across the Elantra, Sorento, Soul and others, and nothing in them points one way: spark plugs come up 11 times and coils 12, as they do across the record.

What is coolant intrusion on a Ford EcoBoost?

Coolant getting into the cylinder, which Ford has written up for two engines. Ford lists the cylinder misfire codes among its signs, alongside low coolant, white exhaust smoke and a rough-running engine, which is why the code is often how owners first hear about it. The two engines:

• The 1.5L EcoBoost. 2014 to 2019 Fusion built on or before June 10, 2019, and 2017 to 2019 Escape built on or before April 8, 2019. Ford's repair is a new short block, the bottom half of the engine with its pistons and crankshaft, and a new head gasket.
• The 2.0L EcoBoost. 2015 to 2018 Edge, and 2017 to 2019 Fusion, MKZ, Escape and MKC. Ford's repair here goes further, to a long block, which is the short block with its cylinder head already fitted.

For the 2.0L, a 2018 Ford message to its dealers puts the cause at corrosion on the engine block and gives the test: pressurize the cooling system to 20 psi, hold it for five hours, and if it drops 4 psi, pull the spark plugs and look for coolant in the cylinders.

Is your Ford still covered?

Only if it's a 1.5L Escape or Fusion, and then it's worth one phone call. Ford program 21N12 pays for a one-time short block repair for coolant intrusion, for 7 years or 84,000 miles from the date the vehicle's warranty started, whichever comes first. It covers 2017 to 2019 Escape and Fusion models with the 1.5L, and the coverage passes to later owners.

The part for cars already past those limits has closed: their owners had until November 30, 2022, and refunds for repairs paid before the owner letter ended the same day. The 7 years still run for a 2019 that went into service late, so the in-service date and the mileage decide it, and a Ford dealer can look up both from the VIN.

We found no matching program for the 2.0L in the federal archive. Its bulletins are repair instructions, so for an Edge or a 2.0L Escape, whether Ford pays depends on the car's own warranty, and the bulletins don't extend it.

What about the Honda piston ring case?

It's an older, settled case, and it explains why a new plug sometimes doesn't last. Honda's bulletins say the piston rings on certain cylinders can rotate and line up, which fouls the spark plug and sets P0301 through P0304.

Honda extended the powertrain warranty for it to 8 years with unlimited mileage from the original purchase, settling a class action, Soto v. American Honda.

It covered the 2008 to 2012 Accord, the 2010 to 2012 Crosstour, the 2008 to 2013 Odyssey and the 2009 to 2013 Pilot. For a car bought new in its model year, eight years ran out long ago. The pattern hasn't: on those cars a plug that fouls again soon after it's replaced is what Honda's bulletin describes, and 24 of the 84 Honda complaints naming P0301 mention piston rings.

What about a Toyota Prius?

Toyota's clearest written case is the intake, not the plug. Toyota's bulletin covers the 2010 to 2015 Prius with the 2ZR-FXE engine, the 2012 to 2015 Prius Plug-in and the 2012 to 2016 Prius V. It ties a misfire under light acceleration to the moments the exhaust gas recirculation system is working, which is when the engine feeds some of its own exhaust back into the intake, and its fix is a new intake manifold, booked at 1.5 hours of labor.

Only 5 of the 332 federal complaints are Toyotas, so for a Corolla or a Camry, the cars people search this code with most, the usual causes above are the answer.

What should you do about a P0301 code?

The first two of the 4 steps below cost nothing:

1. Read every code, not just this one. P0301 alone points at cylinder 1. P0301 beside P0316, P0217, P1285 or P1299 on a Ford is the pattern Ford's coolant intrusion bulletins list, and it changes the whole diagnosis.
2. Move the coil. On an engine with one coil per cylinder, swap cylinder 1's coil with another cylinder's, clear the code and drive. If the misfire follows the coil, it's the coil; if it stays, it's the plug, the injector or the cylinder. The reasoning is on the P0300 page.
3. On a 1.5L or 2.0L Ford EcoBoost, check the coolant first. If the reservoir keeps dropping with no leak underneath, ask for the pressure test Ford gives its dealers: 20 psi held for five hours, then the plugs out to look for coolant.
4. Ask whether a bulletin or program covers the car. Give the VIN. A software update is the commonest bulletin fix for this code, and on a 1.5L Escape or Fusion the answer may be program 21N12. A shop that has checked can name the bulletin; one that hasn't is quoting a guess.

What if P0301 comes back after new plugs and coils?

Then the problem is the cylinder rather than what feeds it, and that's measured rather than swapped. Three things are worth knowing:

• Coolant on the plug. On the Ford engines above, a plug that comes out wet with coolant is exactly what Ford's dealer test ends by looking for.
• The new plug fouls again. On the Honda models above, that's the piston ring pattern Honda's bulletins describe.
• Anything else is a compression question. A cylinder that won't hold compression won't fire whatever the plug, and that's where an owner's own checks end and a shop's measurements begin.

Common questions

Asked most often

What does the P0301 code mean?

It means the engine computer counted too many misfires in cylinder 1. It's an OBD-II code, and its full name is cylinder 1 misfire detected. The usual causes are that cylinder's spark plug, ignition coil or fuel injector.

What is the most common cause of a P0301 code?

A spark plug or an ignition coil: owners name the plug in 100 of 332 federal complaints and the coil in 67. On the 1.5L and 2.0L Ford EcoBoost engines the record points elsewhere, at coolant getting into the cylinder, mentioned in 117 of 140 Ford and Lincoln filings.

Can I drive with a P0301 code?

Not far, and not at all if the check engine light is flashing, which means the misfire is heavy enough to damage the catalytic converter. On a 1.5L or 2.0L Ford EcoBoost, a coolant level that keeps dropping is a second reason to stop.

How much does it cost to fix a P0301 code?

Usually $256 to $572 as US averages, parts and labor: $256 for coils, $299 for spark plugs, $572 for injectors. If it's coolant intrusion on a 1.5L or 2.0L Ford EcoBoost, owners' quotes for a new engine or block run from $5,676 to $16,170.

Can a cylinder 1 misfire fix itself?

The light can go out if the misfire stops, but a worn plug or a failing coil doesn't repair itself, and the code usually returns. Clearing it without a repair also erases the evidence a shop would use.

What does P0316 with P0301 mean?

On a Ford Escape, Edge or Fusion with the 1.5L or 2.0L EcoBoost, it's a pairing Ford's bulletins list for coolant getting into the cylinder. P0316 appears beside P0301 in 45 federal complaints, and every one is a Ford or a Lincoln.

Will Ford pay for a P0301 coolant repair?

On a 2017 to 2019 Escape or Fusion with the 1.5L, possibly: program 21N12 pays for a one-time short block repair for 7 years or 84,000 miles from the warranty start. A Ford dealer can check it from the VIN.

Is P0301 the same as P0300?

No. P0300 means misfires the computer couldn't pin to one cylinder; P0301 names cylinder 1. They can arrive together, and 99 of the 332 filings name both.

Prices are ranges compiled in September 2026 for the US market: counter prices are RockAuto listings, repair averages are CarMD's national figures read in August, and the engine replacement figures are owners' quotes from federal complaints, not prices we researched. 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.