P0302 Code: Cylinder 2 Misfire Detected
Quick Answer
Cylinder 2 isn't firing correctly — combustion is incomplete or absent in that specific cylinder.
At a Glance
What this code means
P0302 is a specific misfire code pointing to cylinder 2. The ECU monitors crankshaft rotational speed; when cylinder 2 fails to produce a proper power stroke, there's a detectable variation in crankshaft speed. Cylinder 2's location in the engine varies by make and model, so a service manual can help identify it physically.
A misfire happens when combustion fails in one cycle. The crankshaft loses speed at that cylinder, which the ECU detects as a misfire event.
Common causes
- Worn or fouled spark plug in cylinder 2
- Failed ignition coil for cylinder 2
- Clogged or leaking fuel injector on cylinder 2
- Low compression in cylinder 2
- Vacuum leak near cylinder 2 intake port
- Faulty spark plug wire (on older vehicles)
Symptoms you might notice
- Rough idle with noticeable vibration
- Flashing or steady check engine light
- Reduced power and fuel economy
- Hesitation during acceleration
- Possible smell of raw fuel from the exhaust
Can you still drive?
If the check engine light is flashing, stop immediately to prevent catalytic converter damage. Steady light — limit driving and get it inspected.
How serious is this code?
High if the misfire is severe or ongoing. A single-cylinder misfire is manageable but should be addressed promptly.
Before you replace parts
Parts replacement is often not the first step. Before buying anything, it's worth checking these basics:
- Check for related codes — a companion code may point to the true root cause
- Inspect wiring, connectors, and grounds around the affected sensor or component
- Look for obvious physical damage: cracks, disconnected hoses, or corrosion
- Clear the code, drive the vehicle, and see if it returns — intermittent codes can come from loose connections
- Verify the part is actually faulty by testing it before replacing it
How to troubleshoot it
- Inspect and replace the cylinder 2 spark plug if worn or fouled
- Swap the cylinder 2 coil with a known-good cylinder coil and see if the misfire moves with it
- Test cylinder 2 compression with a gauge — look for readings well below other cylinders
- Verify the cylinder 2 injector is pulsing with a noid light
- Check for vacuum leaks at the cylinder 2 area of the intake manifold
Tools that may help
These are the types of tools commonly used when diagnosing this code. Having the right tool can save time and help confirm a diagnosis before spending money on parts.
- OBD-II scanner
- Compression tester
- Spark plug socket set
- Multimeter
Estimated repair cost range
Spark plug: $5–$25 per plug. Ignition coil: $50–$150. Fuel injector: $150–$350. Compression test (shop): $80–$150.
Costs vary significantly by vehicle, location, and whether you use OEM or aftermarket parts. These are general ranges for reference only.
When to call a mechanic
If you've completed the basic troubleshooting steps and the code keeps returning, or if you don't have access to the proper diagnostic tools, it's worth consulting a professional. A qualified technician can perform a full diagnosis and confirm the root cause before any parts are purchased. When in doubt, get a professional opinion — it can save you from an expensive misdiagnosis.
Real-world note
Multiple single-cylinder misfire codes appearing together (e.g., P0301 and P0302) may indicate a fuel delivery issue affecting multiple injectors, or a common ignition system problem rather than individual cylinder faults.
Informational purposes only. This guide is for educational reference and is not a substitute for diagnosis by a qualified technician. Repair costs, causes, and symptoms may vary by vehicle make, model, year, and condition. Always consult a licensed mechanic before performing major repairs.