P0307 Code: Cylinder 7 Misfire Detected
🟠 Moderate severity · drivable
Short trips with a steady light are usually fine, but repair it promptly to protect the catalytic converter — and stop immediately if the light flashes.
What P0307 means
The computer has flagged cylinder 7 for misfiring. A single-cylinder code like P0307 is good news diagnostically: the fault is almost always specific to cylinder 7 — its spark plug, ignition coil, or fuel injector — rather than a broad fuel or air problem. That's the key difference from P0300, the random-misfire code that points to shared causes.
Symptoms
- Check engine light on (flashing when severe)
- Rough idle and engine shake
- Loss of power and hesitation
- Reduced fuel mileage
Common causes
- most common: Worn or fouled spark plug on cylinder 7
- common: Failing ignition coil or plug wire for cylinder 7
- common: Clogged or leaking fuel injector on cylinder 7
- less common: Low compression in cylinder 7 from internal wear
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Swap cylinder 7's plug and coil with another cylinder and re-scan to confirm the misfire follows the parts | Yes | $0–20 |
| Replace the cylinder 7 spark plug | Yes | $10–50 |
| Replace the cylinder 7 ignition coil | Yes | $50–200 |
| Have cylinder 7 compression-tested | Mechanic | $100–200 |
Frequently asked questions
Does P0307 point only to cylinder 7?
Yes. A single-cylinder misfire means the fault is nearly always on that cylinder's plug, coil, or injector. A misfire that hops around sets P0300 instead.
How do I isolate P0307 quickly?
Swap the cylinder 7 spark plug and coil to another cylinder and re-scan. If the misfire travels with them, the bad part is identified. If it stays on 7, check the injector and compression.
Is it safe to drive with a P0307?
Briefly with a steady light, yes — but unburned fuel can damage the catalytic converter, and a flashing check engine light means stop and get a tow.
Related codes
P0300
P0300 Code: Random/Multiple Cylinder Misfire Detected
P0306P0306 Code: Cylinder 6 Misfire Detected
P0308P0308 Code: Cylinder 8 Misfire Detected
Related guide: The 10 Most Common Check Engine Codes →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.