P0302: Cylinder 2 Misfire Detected

P0302 quick answer

Severity: Moderate
Can I drive? Short-term, usually yes, if the check-engine light is steady - a single-cylinder misfire rarely leaves you stranded.
Typical fix: $100 - $450

Also written as PO302 or P302.

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What P0302 means

P0302 means a misfire was detected in cylinder 2. As with the other cylinder-specific misfire codes, the cause is almost always the coil, plug, or injector for that cylinder, or a mechanical issue inside it. A quick way to diagnose it is to swap the coil (or plug) from cylinder 2 to another cylinder and see if the misfire follows the part.

Symptoms of P0302

Rough idle
Stumble on acceleration
Flashing check-engine light during a hard misfire
Power and fuel-economy loss

Is it safe to drive with P0302?

Short-term, usually yes, if the check-engine light is steady - a single-cylinder misfire rarely leaves you stranded. Do not put off diagnosis, though: driving on it for long washes oil off the cylinder wall and lets unburned fuel reach the catalytic converter. If the light starts flashing, stop driving - that means the misfire has become severe enough to damage the converter.

Common causes of P0302

Bad ignition coil on cylinder 2
Worn or fouled cylinder 2 spark plug
Clogged or leaking cylinder 2 fuel injector
Vacuum or intake leak near cylinder 2
Low compression in cylinder 2

Listed roughly most-likely first. Confirm with a scan tool and the freeze-frame data before replacing parts.

What the P0302 fix costs

Fix	DIY parts	At a shop
Replace the cylinder 2 ignition coil	$25 - $90	$100 - $250
Replace the cylinder 2 spark plug	$8 - $25	$60 - $150
Test or replace the cylinder 2 injector	$40 - $150	$150 - $450

Ranges are rounded and for the US market only - actual price depends on region, shop labor rates, and the exact make and model.

What a new ignition coil costs, if testing points to it

Parts that commonly fix P0302

Ignition coil - Cause #1 for a single-cylinder misfire - prove it with the coil swap test first
Spark plugs - Cause #2: worn or fouled plugs. Replace as a set, in the heat range your engine specifies
Inline spark tester - Shows whether the coil is delivering spark to that cylinder in seconds
Dielectric grease - A thin coat inside the coil boot stops the arcing and moisture that cause repeat misfires
Compression tester - For when the misfire stays put after coil and plug swaps - rules low compression in or out
OBD-II scanner - Reads and clears codes, and shows live data so you fix the cause rather than the symptom

These open an Amazon search - add your year, make and model, because most of these parts are fitment-specific.

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What P0302 actually means

P0302 is a misfire confined to cylinder 2. The diagnostic logic is the same swap-and-observe approach that works for any cylinder-specific misfire, and it remains the fastest route to a definitive answer. What differs is access: on a transverse V6 or V8, cylinder 2 may sit on the rear bank against the firewall, which turns a ten minute coil swap into an hour with the intake manifold off. Confirm your engine cylinder layout before you start, because assuming cylinder 2 is next to cylinder 1 is not true on every engine.

How to diagnose P0302 step by step

Step 1: Confirm where cylinder 2 physically sits on your engine Cylinder numbering follows the manufacturer firing order, not a left-to-right count. On many V engines the even cylinders are all on one bank. Look up your specific layout before removing anything, or you will test the wrong cylinder entirely.
Step 2: Swap the cylinder 2 coil with an accessible neighbour Move it to a cylinder you can reach easily, clear the codes, and drive. If the misfire follows the coil to its new cylinder, the coil is the fault. If P0302 persists, the coil is good and the problem stays with cylinder 2.
Step 3: Swap the injector if the coil tested good Same method, same logic. A migrating code confirms the injector. On engines where the rear bank injectors sit under the intake manifold, do this at the same time as any other rear-bank work rather than going in twice.
Step 4: Inspect the cylinder 2 plug against a known-good one The plug records how that cylinder has been running. Oil, fuel wash, overheating, and a widened gap all leave distinct signatures. Judging one plug in isolation is guesswork - compare it directly against one from a healthy cylinder.
Step 5: Compression test cylinder 2 and its neighbours When spark and fuel are both good, mechanical condition is what is left. A cylinder reading more than about 15 percent below the others explains the misfire and changes the entire scope of the repair.
Step 6: Check for a vacuum leak at the cylinder 2 intake runner A cracked intake gasket or split vacuum line feeding one runner leans out that single cylinder and misfires it with perfectly healthy ignition parts. Spray carb cleaner around that runner and watch for an idle change before assuming the worst.

The most common P0302 misdiagnosis

Assuming cylinder 2 is physically adjacent to cylinder 1 is a genuine and common error, and it leads to testing the wrong cylinder entirely. Cylinder numbering follows the firing order and varies by engine - confirm your layout first.

Tools you need for P0302

Long extension and swivel socket set - Rear-bank cylinders on transverse V engines cannot be reached with a standard ratchet.
Spark plug socket with rubber insert - Essential for extracting a plug from a deep well without dropping or cracking it.
Inspection camera - Lets you see a rear-bank coil connector you physically cannot get your head near.

Parts you may need for P0302

Spark plugs, full set - If the rear bank is coming apart, do every plug while you are in there.
Intake manifold gasket set - Required if you pull the manifold for rear-bank access, and the fix for a single-runner vacuum leak.

P0302: DIY or pay a shop?

Difficulty: Easy to Moderate. Time: 0.5 - 4 hours. DIY parts: $40 - $220. Shop total: $150 - $500.

Genuinely easy on an inline four where every cylinder is in plain sight. On a transverse V6 with cylinder 2 on the rear bank, the diagnosis is identical but the access is the whole job - budget for pulling the intake manifold and doing plugs, coils, and gaskets in one pass rather than going back in twice.

How to stop P0302 coming back

Do plugs and coils as a set on hard-to-reach banks. When labour is the dominant cost, replacing only the failed part guarantees you pay that labour again when the next one goes. On a rear bank the marginal cost of doing all of them while you are already in there is small. Log the full set in ServiceSage with the mileage and you will know exactly when the next interval lands - before you have to take the manifold off again. Track this maintenance free.

P0302 FAQ

How much does it cost to fix P0302?

Typical US independent-shop repair cost for P0302 runs about $100 - $450, depending on the root cause. Common fixes: Replace the cylinder 2 ignition coil (about $100 - $250 at a shop); Replace the cylinder 2 spark plug (about $60 - $150 at a shop); Test or replace the cylinder 2 injector (about $150 - $450 at a shop).

Will P0302 clear itself?

No, not on its own. P0302 will keep coming back every time the relevant monitor re-runs until the underlying cause is actually repaired - clearing it with a scan tool without fixing what triggered it only delays the light coming back on.