P0302 — Cylinder 2 Misfire Detected
The engine control module has detected a combustion misfire isolated to cylinder 2.
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What the P0302 code means
P0302 pins the misfire to cylinder 2. Like all P030X codes, it means that cylinder's air-fuel mixture failed to ignite correctly at least often enough for the computer to flag it.
The diagnostic path is the same as any single-cylinder misfire: verify that cylinder's spark, fuel delivery, and mechanical integrity, and compare results against a known-good cylinder.
Common symptoms
- Check-engine light on or flashing
- Rough or shuddering idle
- Stumble on acceleration
- Reduced power
- Possible exhaust pop or unburned fuel smell in severe cases
Possible causes
- Worn or fouled spark plug at cylinder 2
- Weak or failing ignition coil
- Clogged fuel injector
- Low compression — valve seating, rings, or head gasket at that cylinder
- Vacuum leak at that intake runner
- Ignition wiring or connector damage
Diagnostic considerations
Use the coil-swap test: if moving the coil moves the misfire code, replace the coil. If it stays with cylinder 2, test the plug, injector, and compression in that order.
On engines where cylinders share an ignition coil pack, one bad section of the pack can misfire the paired cylinder too — check the pairing for your engine.
What a technician may inspect
- Spark plug condition at cylinder 2
- Coil swap test with a neighboring cylinder
- Injector balance and flow
- Compression test for cylinder 2
- Intake runner and vacuum sealing near that cylinder
Common mistakes
- Assuming cylinder numbering without checking the manufacturer layout
- Replacing the coil without confirming the misfire follows it
- Missing a shared-coil design where one coil section affects two cylinders
When professional inspection is appropriate
Related codes
Related glossary terms
FAQ
Frequently Asked Questions
How is P0302 different from P0300?
P0302 names one cylinder; P0300 is random or across multiple cylinders. A single-cylinder code is usually simpler to isolate.
Can I test this myself?
A coil swap and plug inspection are approachable on many vehicles. Injector and compression testing usually call for professional tools and experience.
Will replacing the spark plug fix it?
It often does when the plug is worn or fouled — but the code only confirms the cylinder, not the part. Test before buying.
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