What does code P0301 mean on a Subaru and is it safe to drive?
P0301: Cylinder 1 Misfire Detected. Here's what it means on your Subaru, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
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What this code means
The PCM has detected a misfire specifically on cylinder 1. Similar to P0300, but pinned to a single cylinder.
Common causes for your Subaru
- Worn or fouled spark plug on cylinder 1
- Failing ignition coil or coil-on-plug
- Leaking or clogged fuel injector
- Low compression in cylinder 1
Symptoms
- Check Engine Light (often flashing when misfire is severe)
- Rough idle or shaking, especially at low RPM
- Loss of power under load
Typical fixes
- Replace spark plug and/or coil on cylinder 1
- Test and clean or replace the injector
- Perform compression test and repair internal issues if needed
Repair cost range
For a Subaru, repairs for P0301 often fall between $150 and $900, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Subaru
On EJ-series Subaru engines, a P0301 often signals a head gasket leak on cylinder 1 allowing coolant into the combustion chamber. Check for white exhaust smoke at startup and a milky residue on the oil cap. Ignition diagnosis should come after ruling out the head gasket.
Most commonly affected models
Outback EJ25 2000–2009Forester EJ25 2006–2010Impreza WRX EJ20 2002–2014