P0301 Code: Cylinder 1 Misfire, Every Cause, and 2026 Repair Cost Guide

In this article 11 sections

1. What Does P0301 Mean?
   1. P0301 Code – Quick Diagnostic Intelligence
   2. Cylinder 1 Misfire Detected
   3. P0301 vs P0300
2. Symptoms of a P0301 Code
   1. Rough Idle and Shaking
   2. Power Loss
   3. Flashing Check Engine Light
3. Common Causes (Cheapest First)
   1. Worn Spark Plug
   2. Failing Ignition Coil
   3. Clogged Injector
   4. Low Compression on Cylinder 1
4. How to Diagnose P0301 Yourself
   1. Swap the Coil to Another Cylinder
   2. Inspect Plug and Injector
   3. Compression Test
5. How Much Does It Cost to Fix P0301?
   1. Plug or Coil ($50 to $300)
   2. Injector or Compression Work
6. Vehicle-Specific Notes
   1. P0301 on Honda
   2. P0301 on Toyota
7. Can You Drive With a P0301 Code?
   1. Flashing Light Means Stop
8. How to Prevent P0301
9. Wrapping Up Your P0301 Fix
10. Frequently Asked Questions About the P0301 Code
11. Data Sources and Verification

A P0301 code points straight at a misfire in cylinder 1, and that one fact makes the whole job easier. A random misfire can hide anywhere in the engine. But this trouble code hands us a clear starting point. So we can skip the guesswork and go right to the parts that matter most.

Single-cylinder misfires are among the most common check engine codes. Often, the fix costs far less than drivers expect. The check engine light looks scary at first. However, the real repair often comes down to one worn plug or one tired coil.

In this guide, we walk through what the code means and the symptoms to watch for. After that, we cover the cheapest fixes first and share a simple home test. Most importantly, we show honest 2026 costs and add notes for Honda and Toyota owners. So grab your scanner, and let us get moving.

If your scan also returned a code for cylinders across the whole engine rather than just one, our P0300 code guide covers the random multiple cylinder misfire diagnosis in full detail.

What Does P0301 Mean?

An engine misfire happens when a cylinder fails to burn its fuel and air the right way. The ignition system needs a strong spark at the perfect moment. But when that spark weakens, the burn falls apart. As a result, power drops and the engine shakes.

Cylinder 1 Misfire Detected

When the scanner reads “cylinder 1 misfire detected,” it names the exact spot to check. Firstly, that saves you real time. Secondly, it saves money on parts you do not need. So you can focus on one cylinder instead of six or eight.

Finding cylinder 1 matters here. Every engine follows its own firing order and layout. So check the manual before touching anything. Likewise, a quick label on the coil helps during testing.

P0301 vs P0300

The difference between p0301 vs p0300 comes down to focus. P0301 flags one cylinder, which is cylinder 1. But P0300 means the computer sees a random misfire across several cylinders. So P0301 is the friendlier code to chase.

A single-cylinder code usually points to a failed part on that one spot. Meanwhile, a random misfire often means fuel, vacuum, or timing trouble for the whole engine. In short, one cylinder is easier than many.

Symptoms of a P0301 Code

The p0301 code symptoms show up fast, and most drivers feel them before they see the light. The car runs rough and loses its smooth pull. So the warning signs are hard to miss. Below, we cover the three most common ones.

Rough Idle and Shaking

A shaky idle is usually the first clue. The engine stumbles at a stoplight and the whole car trembles. But the shaking often eases once you get moving. Still, that rough feel is your engine begging for help.

Power Loss

Weak power is the next big sign. The car feels slow and lazy on the highway. So passing other cars gets harder than normal. Meanwhile, your fuel economy quietly slips as the engine works overtime.

Flashing Check Engine Light

A flashing check engine light is the serious one. A steady light means “check me soon.” But a blinking light means a live misfire is dumping raw fuel into the exhaust. So you should stop as soon as it is safe.

Common Causes (Cheapest First)

Start with the cheap stuff, because it often pays off. A p0301 code fix often costs less than a nice dinner out. So do not panic when the light comes on. Below, we list the top causes from cheapest to priciest.

Worn Spark Plug

A tired p0301 spark plug is one of the most common causes. Plugs wear down and their gap grows too wide over time. As a result, the spark gets weak and misses. So a fresh plug fixes many misfires for very little money.

Failing Ignition Coil

A bad p0301 ignition coil is a close second. The coil feeds high voltage to the plug on cylinder 1. But when it cracks or overheats, the spark fades. So swapping the coil often clears the code fast.

Clogged Injector

A dirty p0301 fuel injector can starve the cylinder too. The injector sprays fuel, and gunk can block that spray. Meanwhile, the cylinder runs lean and misfires. So a good cleaner or a new injector brings it back.

Low Compression on Cylinder 1

Low compression on cylinder 1 is the costly one. It points to worn rings, a burnt valve, or a bad gasket. So this fix takes more time and skill. But it is also the rarest cause on the list.

How to Diagnose P0301 Yourself

You can test this misfire at home with basic tools. A scanner, a wrench, and some patience go a long way. So many drivers save real cash by checking first. Below is a sensible order to follow.

Swap the Coil to Another Cylinder

The coil swap is the classic first test. Move the coil from cylinder 1 to cylinder 2, then clear the code. But watch where the misfire goes next. If it jumps to cylinder 2, the coil is the culprit.

Inspect Plug and Injector

Next, pull the plug and give it a close look. A cracked tip, black soot, or heavy gap tells the story. Meanwhile, listen to the injector with a screwdriver to your ear. A steady click means it still fires.

Compression Test

A compression test is the final step. Thread a gauge into cylinder 1 and crank the engine. But compare that number to the other cylinders. A low reading confirms deeper trouble inside.

How Much Does It Cost to Fix P0301?

Most drivers want the price first, so let us be straight. A plug or coil job is cheap and quick. But injector or compression work climbs higher. Below is a clear 2026 cost table to guide you.

Source: 2026 US shop rate averages and retail parts pricing. Costs vary by vehicle make, model year, and region.

Plug or Coil ($50 to $300)

A plug or coil is the best-case bill. So most drivers land between $50 and $300 total. Certainly, doing it yourself saves the labor charge. And the parts are easy to find at any store.

Injector or Compression Work

The p0301 repair cost climbs once injectors or valves enter the picture. An injector job runs a few hundred dollars in 2026. But compression repair can pass $1,000 fast. So the overall misfire repair cost really depends on the root cause.

Vehicle-Specific Notes

Different makes wear differently, and owners report some clear patterns. Some engines burn through coils, while others love fresh plugs. So a few brand notes help you plan. Below we cover the two we get asked about most.

P0301 on Honda

A p0301 honda case usually traces back to coils or plugs. Many Civics and Accords use long-life iridium plugs replaced around the 100,000-mile mark, as the Maintenance Minder or owner’s manual directs. But high heat can cook a coil early. So we check both parts first on these cars.

Our 2017 Honda Civic full review covers the maintenance intervals relevant to this pattern in detail. And our 2025 Honda Civic Hybrid review covers the current generation for owners of newer models tracking the same coil and plug wear pattern.

P0301 on Toyota

A p0301 toyota code often follows the same path. Camrys and Corollas run reliably, yet coils still fail with age. Meanwhile, carbon buildup can nudge a misfire on higher-mileage engines. So a coil swap and a good cleaning usually solve it.

Our Toyota Corolla 2026 review and our full details of Toyota RAV4 guide cover the maintenance patterns and service intervals for the two Toyota engines most commonly affected by this misfire pattern.

Can You Drive With a P0301 Code?

Sometimes you can drive a short way, but caution is key. A mild, steady misfire may let you limp home. But hard driving makes the damage worse. So we treat every misfire as a reason to slow down.

Flashing Light Means Stop

A flashing light changes everything. It warns that raw fuel is cooking your catalytic converter right now. So pull over and shut the engine off when it is safe. A converter costs far more than a plug or coil.

How to Prevent P0301

Prevention is cheaper than any repair, and it is easy. Change your plugs on schedule and use quality fuel. So carbon and wear stay under control. Likewise, a yearly ignition system check keeps surprises away.

We also suggest a good fuel cleaner every few thousand miles. It keeps each injector spraying clean. Meanwhile, fresh air filters help the burn stay strong. In the same vein, quick action on any small misfire stops big bills later.

Wrapping Up Your P0301 Fix

A P0301 code sounds scary, but it is one of the friendliest misfire codes around. It points to cylinder 1 and lets you fix one clear problem. So start cheap with the plug and coil, then work deeper only if needed. To sum up, most drivers clear this code for well under a few hundred dollars.

Certainly, a little home testing goes a long way here. Swap the coil, read the plug, and let the car tell you the truth. For more help, see our full P0300 guide and our other misfire repair walkthroughs. And drop us a comment with your make and mileage, so we can point you the right way.

Related guides: the full trouble code library and U0100 Code.

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