P0301 on Volvo: How to Diagnose & Fix
Cylinder 1 Misfire Detected
1 Volvo model · 1 documented issue · $100-$500 repair
P0301 on Volvo by model: symptoms, diagnosis and fix
Nearly 20% of C30 owners report rough idle issues according to Consumer Reports data. The rough idle can be caused by several factors: failing ignition coils, ETM (Electronic Throttle Module) issues, PCV system failures, and vacuum leaks. The 2.5L turbo I5 is particularly sensitive to PCV system degradation which causes positive crankcase pressure and oil ingestion into the intake. The 2.0L I4 models are less affected but can develop similar idle issues from ignition coil failures.
Common Symptoms
- Rough or uneven idle
- Engine hesitation on light throttle
- Intermittent misfires at idle
- Engine vibration felt through steering wheel at idle
- Slight RPM fluctuation at idle
How to Fix
Start diagnostics with the PCV system — check the PCV valve and breather hose for blockage or collapse. Replace ignition coils and spark plugs if misfires are present. Clean the electronic throttle body. Check for vacuum leaks using a smoke test. The PCV system on the 2.5L turbo requires periodic replacement of the breather box/oil trap assembly ($50-$150 for parts).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- CRP 202171 Volvo RNC five-cylinder PCV diaphragm
replace a confirmed torn oil-filter-housing PCV diaphragm causing abnormal crankcase vacuum and idle symptoms Fitment/availability: Applicable 2008-2013 Volvo C30 late-RNC turbo five-cylinder oil-filter-housing diaphragm branch; confirm …
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Owner tips & cautions
- TipCheck the PCV breather box first — it's the #1 cause of rough idle on the 2.5T engine and is a cheap fix.
- TipReplace all ignition coils at once rather than chasing individual failures — they tend to fail in sequence.
Sources for this issue (1)
P0301 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0301 mean on a Volvo?
P0301 stands for "Cylinder 1 Misfire Detected." P0301 means the engine computer detected a misfire specifically in cylinder 1 — the spark didn't ignite the fuel properly, or the fuel/air mix didn't burn as it should. The computer detects this by sensing tiny variations in crankshaft speed each time a cylinder fires. A misfire wastes fuel, raises emissions, and can damage the catalytic converter if it's severe or persistent (a flashing check engine light usually warns of active, converter-damaging misfires). Because the code points to one specific cylinder, the cause is usually an ignition, fuel, or compression problem isolated to that cylinder. On Volvo it is documented across 1 model: C30.
What are the most common causes of P0301?
The most common causes of P0301 are: Worn or fouled spark plug in cylinder 1, Failed ignition coil or coil pack for cylinder 1, Faulty or clogged fuel injector for cylinder 1, Vacuum or intake air leak affecting that cylinder, Bad spark plug wire (on applicable engines), Low compression (worn rings, leaking or burnt valve, head gasket), Carbon buildup on intake valves, Wiring or connector fault to the coil or injector. The specific cause varies by vehicle.
How much does it cost to fix P0301 on a Volvo?
Published repair estimates on Volvo range from $100 to $500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0301 on a different make?
View P0301 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.