P0302 means the engine control module has detected a misfire specifically in cylinder 2 — the ignition system failed to properly combust fuel in that one cylinder enough times to be flagged, while other cylinders are firing normally. This is the single-cylinder counterpart to our P0300 random/multiple cylinder misfire guide, and completes the full single-cylinder family on this site alongside P0301 (cylinder 1), P0303 (cylinder 3), and P0304 (cylinder 4) — the diagnostic approach is nearly identical across all four, just narrowed to a specific spark plug, coil, or injector.
What Does P0302 Mean?
The engine control module monitors crankshaft speed variations to detect when a specific cylinder isn’t contributing its expected share of power on each combustion cycle. When cylinder 2 specifically shows this pattern repeatedly, the module stores P0302. Because the code identifies the exact cylinder, it points a technician directly at that cylinder’s spark plug, ignition coil, fuel injector, or a compression issue specific to that cylinder — a significant narrowing compared with the broader P0300 code, which fires when the pattern doesn’t cleanly point to one cylinder.
Common Symptoms
- Check engine light on, flashing if the misfire is severe or actively damaging the catalytic converter
- A rough, uneven idle or a noticeable engine shake, particularly at idle
- Reduced power and hesitation on acceleration
- Reduced fuel economy
- An audible popping or stumbling sound from the engine, especially under load
Common Causes, Most Likely First
- A worn or fouled spark plug in cylinder 2 — the single most common cause of any isolated single-cylinder misfire code.
- A failing ignition coil serving cylinder 2 (on coil-on-plug or coil-near-plug designs), which can fail independently of the coils on other cylinders.
- A clogged or failing fuel injector on cylinder 2, delivering too little fuel to that cylinder specifically.
- A vacuum leak affecting cylinder 2’s intake runner specifically, less common than a general vacuum leak but possible depending on manifold design.
- Low compression in cylinder 2 from a worn valve, piston ring, or head gasket issue isolated to that cylinder — more serious and requires a compression test to confirm.
How to Diagnose It
- Pull the code with an OBD-II scanner and check for any accompanying codes — see our OBD-II scanner guide for what a scan can and can’t tell you on its own.
- Inspect and, if needed, swap the spark plug and coil from cylinder 2 with a known-good cylinder — if the misfire code follows the swapped part to a different cylinder, you’ve found the faulty component; if it stays on cylinder 2, the cause is elsewhere (injector or compression).
- Check fuel injector function for cylinder 2 specifically if the spark components test fine.
- Run a compression test on cylinder 2 if electrical and fuel delivery components all check out, to rule in or out a mechanical cause.
Never work under a vehicle supported only by a jack. Use axle stands on firm, level ground, chock the wheels that stay down, and leave the car in gear or Park with the handbrake on. A jack lifts; stands hold.
Possible Fixes
| Cause | Fix | Typical cost |
|---|---|---|
| Worn spark plug | Replace the spark plug(s) | $40 – $150 |
| Failing ignition coil | Replace the coil | $100 – $250 |
| Clogged/failing fuel injector | Clean or replace the injector | $150 – $400 |
| Low compression (mechanical) | Further diagnosis, engine repair | Varies widely |
Can I Keep Driving With This?
Short trips only, and address it reasonably soon — a single-cylinder misfire strains the catalytic converter over time and can worsen into a more severe, flashing-light misfire if left unaddressed. See our P0300 guide for the general urgency guidance that applies here as well.
When to See a Mechanic
Reasonably soon rather than urgently, unless the check engine light is flashing (which means stop driving immediately) — see our check engine light flashing guide. More in our trouble codes section.
Frequently Asked Questions
What does P0302 mean?
It means the engine control module has detected a misfire specifically in cylinder 2 — that cylinder isn’t combusting fuel properly on a consistent basis while other cylinders fire normally.
Is P0302 the same as P0300?
No — P0300 indicates a random or multiple-cylinder misfire that doesn’t isolate to one specific cylinder, while P0302 points directly at cylinder 2, which meaningfully narrows the diagnosis.
What’s the most common cause of a P0302 code?
A worn or fouled spark plug in cylinder 2 is the most common cause, followed by a failing ignition coil serving that cylinder.
How do I know if it’s the spark plug, coil, or injector?
Swap the spark plug and coil from cylinder 2 with a known-good cylinder — if the misfire code moves to the new cylinder, you’ve found the faulty part; if it stays on cylinder 2, the cause is likely the injector or a mechanical issue.
Is it safe to drive with a P0302 code?
Short trips only — get it addressed reasonably soon, since a prolonged misfire can damage the catalytic converter. Stop driving immediately if the check engine light is flashing.
How much does it cost to fix P0302?
Often $40–$150 for a spark plug, up to $250 for an ignition coil, or $150–$400 if a fuel injector needs replacement.
