OBD2 Code P0303: Cylinder 3 Misfire Detected
The P0303 code means Cylinder 3 Misfire Detected. Estimated repair cost: $80 – $1000.
✅ OK TO DRIVE (short term). Have it diagnosed at your next convenience. Monitor for new symptoms.
📋 Diagnostic Reference
| OBD2 Code | P0303 |
| Category | Powertrain |
| Severity | Check Soon |
| Repair Cost | $80 – $1000 |
| Can You Drive? | ⚠️ Yes but drive directly to a shop — limit distance |
🔍 Symptoms
- Engine vibration
- hesitation
- rough idle
⚠️ Most Likely Causes (in order of probability)
- Bad spark plug cylinder 3
- failed coil
- stuck injector
- vacuum leak
🛠️ Diagnostic Procedure
Step 1: Inspect cylinder 3 spark plug
Inspect cylinder 3 spark plug
Step 2: Swap ignition coil
Swap ignition coil
Step 3: Noid light test on injector
Noid light test on injector
Step 4: Compression test.
Compression test.
ASE Certified Review: This diagnostic guide has been reviewed by an ASE-certified master technician. Diagnostic steps follow industry best practices per SAE J1979 and OEM service procedures. Always verify with a qualified mechanic before performing repairs.
Technician's Notes: Same diagnostic approach as P0301/P0302 — swap and isolate.
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Dealerships charge $100-$200 just to scan your car and read the code. A $20 Bluetooth OBD2 scanner gives you the same information in 30 seconds — and it works with free apps on your phone. Read and clear codes yourself before deciding if you need a mechanic.
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Data Sources: Diagnostic information compiled from SAE J1979 OBD2 standards, OEM service manuals, and ASE master technician field experience. Reviewed for technical accuracy. Repair cost ranges are national estimates and vary by location. Always verify with a qualified mechanic.