P0302: Cylinder 2 Misfire Detected
P0302 means the engine computer detected a misfire on cylinder 2, which can cause rough running, shaking, and a flashing check engine light. The most common fix is a worn spark plug or bad ignition coil, usually about $150 to $450 at an independent shop.
- Severity
- High
- Can I drive?
- Drive with caution
- DIY?
- Possible with some experience
- Repair cost range
- $100 – $2,500
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What does P0302 mean?
A misfire means cylinder 2 is not burning fuel the way it should. That can happen when the spark is weak, fuel delivery is poor, or the cylinder has a mechanical problem. The engine computer watches crankshaft speed and firing pattern, and when it sees cylinder 2 fail to contribute properly, it sets P0302. If the misfire is severe enough, the check engine light may flash to warn you that the catalytic converter can be damaged.
Common symptoms
- Rough idle
- Engine shaking
- Hesitation or stumble on acceleration
- Loss of power
- Check engine light on or flashing
- Bad fuel economy
Causes, fixes and costs
P0302: Cylinder 2 Misfire Detected
General guide for most cars. Your car may differ.
A steady misfire can damage the catalytic converter and make the engine run poorly. If the check engine light is flashing, the engine is shaking badly, or the car is losing power hard, stop driving and have it towed.
Most likely causes
- 1
Worn or fouled spark plugHigh
A worn plug often causes rough idle, hesitation, and a single-cylinder misfire that stays on cylinder 2. It is more likely if the plugs are overdue or the misfire gets worse under load.
Quick check: Inspect cylinder 2 spark plug for heavy wear, oil fouling, carbon buildup, or a cracked insulator.
- 2
Bad ignition coil or coil bootHigh
A weak coil can cause an intermittent or constant misfire on cylinder 2, often with shaking and a flashing light during acceleration. If the misfire moves when the coil is swapped with another cylinder, the coil is the problem.
Quick check: Swap the coil from cylinder 2 with another cylinder and see whether the code changes to that cylinder.
- 3
Fuel injector problemMedium
A clogged or failed injector can cause a single-cylinder misfire, lean running on that cylinder, and a stumble at idle or on acceleration. This is more likely if the plug and coil look good but cylinder 2 still misfires.
Quick check: Listen for injector clicking with a stethoscope and compare cylinder 2 injector operation to the others.
- 4
Compression or valve issueMedium
Low compression from a burned valve, worn rings, or head-gasket issue can cause a persistent misfire that does not go away with ignition part swaps. It is more likely if the misfire is constant and the engine also has low power or uneven idle.
Quick check: Perform a compression test or leak-down test on cylinder 2.
Can you fix it yourself?
Possible with some experience
Difficulty: Moderate. Spark plugs and ignition coils are reasonable DIY checks on many cars if you have basic tools and know how to work safely around the ignition system. Compression and injector diagnosis usually need better test tools, so if swaps do not pinpoint the fault, ask the shop to test cylinder 2 spark, fuel, and compression.
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- Read codes and note whether the misfire is constant or only under load.
- Inspect and, if due, replace the cylinder 2 spark plug.
- Swap the cylinder 2 ignition coil with another cylinder and clear the code.
- Drive briefly and see whether the misfire code follows the coil.
- Check the cylinder 2 coil boot and plug well for oil or moisture.
- If ignition parts do not fix it, test the injector and compression on cylinder 2.
Estimated repair cost
$100 – $250
Spark plug replacement for one cylinder: parts and labor; cost can be higher if plugs are hard to access
- Ignition coil replacement$150 – $450
- Fuel injector replacement or cleaning$180 – $650
- Compression-related engine repair$500 – $2,500
- PCM or wiring repair$120 – $600
Prices vary by engine layout, parts quality, and local labor rates.
Frequently asked questions
Can I drive with code P0302?
If the engine is only slightly rough and the light is steady, you may be able to drive gently for a short time. If the light is flashing or the engine is shaking badly, do not keep driving because you can damage the catalytic converter.
What is the most common fix for P0302?
The most common fix is a worn spark plug or a bad ignition coil on cylinder 2. Many shops start by inspecting and swapping ignition parts before moving to fuel or compression tests.
Will P0302 clear itself?
It can go away temporarily if the misfire is intermittent, but the problem usually comes back unless the cause is repaired. Clearing the code without fixing the issue only hides the symptom.
Can a bad injector cause P0302?
Yes, a clogged or failed injector can cause a misfire on cylinder 2. It is less common than spark plug or coil problems, but it should be checked if ignition parts test good.
Will P0302 make my car fail emissions or inspection?
Yes, a misfire code usually means the engine is not running cleanly enough for an emissions check. In many states, the check engine light or stored misfire code will cause an inspection failure.
Related codes
Related problems
This guide covers most cars and is general advice, not an inspection. Prices are typical US independent-shop ranges and vary by region, car and shop. If your brakes, steering or a warning light feel unsafe, stop driving and contact a mechanic.