P0303: Cylinder 3 Misfire — Causes and Fixes
Key Takeaway
P0303 isolates the misfire to cylinder 3. Quick diagnosis guide.
P0303 = Cylinder 3 Misfire
| Component | Check | Cost |
|---|---|---|
| Spark plug | Gap, wear, fouling | $20 – $40 |
| Ignition coil | Cracks, carbon tracking | $50 – $150 |
| Fuel injector | Resistance test, spray pattern | $150 – $300 |
| Compression | Compression test | $1,000+ if low |
| Wiring | Connector integrity | $50 – $200 |
Cylinder 3-Specific Notes
On inline-4 engines, cylinder 3 is in the middle and can run hotter. On V6 engines, cylinder numbering varies by manufacturer — check your service manual.
The Swap Test
Swap coil or plug with another cylinder. Clear code. If misfire follows the part, you found the problem.
ProHow Steer Helps
Steer identifies P0303 and guides you to the right cylinder location for your specific vehicle.
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