2008 Subaru P0303: What It Means & Is It Safe to Drive?
P0303 on the 2008 Subaru: Cylinder 3 Misfire Detected. Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
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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 on the 2008 Subaru
- 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
For a 2008 Subaru, repairs for P0303 typically fall between $150 and $900, depending on the root cause and labor rates in your area.
Known issues on Subaru
EJ-series Subaru P0303 should prompt a head gasket check before any other diagnosis. Cylinder 3 on the rear-right of Subaru's boxer layout is one of the most common head gasket failure points on EJ251 and EJ253 engines.
Most commonly affected models
Outback EJ25 2000–2009Forester EJ25 2006–2010Legacy 2.5GT EJ255 2005–2009