P0302high severityDo not driveP0302 Code: Cylinder 2 Misfire Detected
Written in plain English and reviewed by the eli5cars editorial team · Last reviewed June 2026
What it means in plain English
Each cylinder in your engine fires in a precise sequence — spark plug ignites the air-fuel mix, the piston pushes down, and the engine makes power. P0302 means cylinder number 2 failed to fire correctly on enough strokes that the ECM noticed and flagged it. The engine is essentially running on one fewer cylinder than it should be, which you'll often feel as a rough idle, stumble under acceleration, or a rhythmic shake.
⛔ Do not drive with this code active
This fault can cause immediate mechanical or safety damage. Have the vehicle towed or inspected before driving.
Most likely causes — ranked
#1 Failed or fouled spark plug in cylinder 2
most likelyFix: Remove the cylinder 2 spark plug and inspect. A worn electrode gap, cracked insulator, carbon fouling, or oil deposits all prevent proper ignition. Replace the plug (and ideally all plugs if high-mileage). This is the single cheapest first step and solves the misfire roughly half the time.
#2 Failed ignition coil on cylinder 2
likelyFix: Most modern engines use a coil-on-plug (COP) design — one coil per cylinder. A failing coil produces a weak or absent spark. A quick diagnostic trick: swap the cylinder 2 coil with a coil from another cylinder and see if the misfire code moves to that cylinder (e.g., P0303). If it follows the coil, replace the coil.
#3 Clogged or leaking fuel injector on cylinder 2
likelyFix: A clogged injector delivers too little fuel; a leaking injector floods the cylinder. Either condition causes a misfire. Try a bottle of fuel system cleaner first. If the misfire persists, a shop can perform an injector balance test or flow test to confirm. Replacement is straightforward but requires fuel rail disassembly.
#4 Low compression in cylinder 2 (worn rings, burned valve, or head gasket leak)
possibleFix: If plugs, coils, and injectors check out, a compression test on cylinder 2 is the next step. Low compression relative to other cylinders points to internal engine wear — piston rings, a burned exhaust valve, or a head gasket failure between cylinders. These repairs are significantly more expensive.
Check engine light on? Get a free code scan
If your check engine light is on, most auto-parts stores (AutoZone, O'Reilly, Advance) will read the code for FREE — no purchase required, just walk in. Bring the code back here and look it up at eli5cars.com/obd2 for the plain-English explanation.
Note: a scan only helps when there's an active fault code. For purely mechanical symptoms (noises, vibrations, leaks), a scan may show nothing — the suspects listed above are your starting point.
Want to read the codes yourself?
First, the free option: AutoZone, O’Reilly, and Advance Auto Parts read your codes for free — no purchase needed. That’s the cheapest way to get the code to look up here. If you’d rather have your own so you can check anytime (and clear a code after a fix), the Veepeak OBDCheck BLE is an inexpensive, reliable plug-in reader that pairs with a free phone app and works on any car sold since 1996.
See the Veepeak OBD2 scanner on AmazonAffiliate link — we may earn a commission at no extra cost to you. Details.
Frequently asked questions
Is it safe to drive with a P0302 misfire?
No — not for any extended distance. A cylinder 2 misfire sends raw unburned fuel into the exhaust system, which can overheat and destroy your catalytic converter within a few hundred miles. Drive to the nearest parts store or shop, but don't use the vehicle as normal until the misfire is fixed.
Can I diagnose P0302 for free?
Yes. AutoZone, O'Reilly Auto Parts, and Advance Auto Parts will scan your OBD2 codes for free. They'll confirm P0302 and any companion codes (like P0300 for random misfire). From there, the swap test — moving the cylinder 2 coil to another position — is free to do yourself and narrows the cause immediately.
P0302 came on with P0300 — what does that mean?
P0300 is a random/multiple misfire code; P0302 pinpoints cylinder 2 as the source. This combination is common — the cylinder 2 misfire is often severe enough to also trigger the random misfire threshold. Fix the cylinder 2 issue and P0300 will typically clear with it.
I replaced the spark plug and coil — P0302 is still there. What now?
Move on to the fuel injector (inspect for clogging or leaking) and then do a cylinder compression test. A compression reading below 120 psi, or more than 15% lower than the other cylinders, suggests an internal engine problem — worn piston rings, a burned valve, or a head gasket issue.