OBD-II trouble code
P0302: Cylinder 2 Misfire Detected
The engine computer detected a misfire specifically in cylinder 2. Diagnosis is more targeted than P0300 — the bad part is on or feeding cylinder 2. The check engine light may be flashing; pull over if it is.
Quick facts
- System
- Powertrain
- Category
- Ignition and Misfire
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $50 – $1,500
- DIY difficulty
- Intermediate DIY
What does P0302 mean?
A misfire is a cylinder that fails to combust properly. The engine control module (ECM) detects misfires by monitoring crankshaft speed — a healthy combustion event accelerates the crankshaft slightly, and the ECM watches for the missing acceleration that signals a failed combustion event. When the ECM isolates the misfire to a single cylinder, it sets a cylinder-specific code instead of the generic P0300.
P0302 means the misfire is in cylinder 2. On an inline engine, cylinder 2 is typically the second from the front, next to cylinder 1. On a V-configuration engine, cylinder 2 may be on either Bank 1 or Bank 2 depending on the manufacturer's numbering convention — domestic V8s often place cylinder 2 on Bank 2 (passenger side), while many imports place it on Bank 1 next to cylinder 1. Check the engine service information for the exact layout.
A flashing check engine light during P0302 indicates the misfire is active. Unburned fuel reaches the catalytic converter and can damage it quickly. Pull over safely if the light is flashing. If the light is steady, you can drive directly to a shop, but avoid hard acceleration and don't ignore the code for days.
Common causes
- Worn or fouled spark plug in cylinder 2
- Failing ignition coil for cylinder 2 (most common on coil-on-plug engines)
- Faulty fuel injector for cylinder 2 (stuck, clogged, or leaking)
- Low compression in cylinder 2 from a burned valve, worn rings, or head gasket leak
- Cracked or damaged spark plug wire feeding cylinder 2 (older engines with separate wires)
- Carbon buildup on the intake valve for cylinder 2
- Vacuum leak isolated to the cylinder 2 intake runner
- Improperly installed or wrong-gap spark plug
Symptoms
- Check engine light on or flashing
- Rough idle and engine shaking
- Loss of power on acceleration
- Hesitation or stumble
- Poor fuel economy
- Smell of unburned fuel from the exhaust
- Engine running on one fewer cylinder than normal
Diagnostic steps
- 1.Confirm the code is P0302 alone — additional misfire codes like P0301 or P0303 alongside P0302 may point to a broader problem like a vacuum leak or fuel pressure issue.
- 2.Inspect the spark plug in cylinder 2. Compare its condition to the plugs in the other cylinders.
- 3.Swap the ignition coil from cylinder 2 with the coil from a known-good cylinder. Clear the code and drive. If the misfire follows the swapped coil to the new cylinder, that coil is bad.
- 4.Do the same swap test with the spark plug.
- 5.Test the cylinder 2 fuel injector resistance and confirm it's pulsing with a noid light or scan tool.
- 6.If ignition and fuel test fine, perform a compression test on cylinder 2 to rule out a mechanical problem.
Repair cost
$50 – $1,500
A single spark plug is $10 to $30 plus 15 to 30 minutes of labor. An ignition coil is $40 to $200 plus a short labor time. Fuel injector replacement is $100 to $400 plus 1 to 3 hours of labor. Compression-related repairs (valve job, head gasket) start at $1,000 and climb quickly.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with spark plug replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.