What does code P0303 mean and is it safe to drive?
P0303: Cylinder 3 Misfire Detected. Here’s what it means, what usually causes it, what repairs typically cost, and how urgent it is to keep driving.
PowertrainDrive with caution
Repair cost
$150–$900
System
Powertrain
Urgency
high
What this code means
The PCM has detected a misfire specifically on cylinder 3. Diagnosis follows the same steps as P0301—swap parts to the same position on a known-good cylinder to isolate the fault.
Common causes
- Worn or fouled spark plug on cylinder 3
- Failing ignition coil on cylinder 3
- Leaking or clogged fuel injector
- Low compression on cylinder 3
Symptoms
- Check Engine Light, often flashing under load
- Rough idle or shaking
- Loss of power, hesitation
Typical fixes
- Replace spark plug and coil on cylinder 3
- Test and replace fuel injector
- Compression test if ignition parts don't resolve it
Repair cost range
Repairs for P0303 often fall between $150 and $900, depending on the cause and your vehicle.