P0301 on Infiniti: How to Diagnose & Fix
Cylinder 1 Misfire Detected
1 Infiniti model · 1 documented issue · $150-$900 repair
P0301 on Infiniti by model: symptoms, diagnosis and fix
The Hitachi coil-on-plug units on the VQ37VHR are a recurring failure item on higher-mileage G37s. Heat and electrical stress cause the coil body to blister or bulge, producing a random or single-cylinder misfire, rough idle and flashing check-engine light. Infiniti's bulletin ITB11-017A (cited by owners and parts guides) tells technicians that a P0300-P0306 misfire with a blistered, deformed or melted coil outer surface indicates coil failure. On the VQ37 the rear bank coils are buried under the intake plenum, which drives labor cost.
Common Symptoms
- Rough idle or shaking at idle
- Flashing check engine light under load
- Misfire counts on one or more cylinders
- Hesitation and power loss
How to Fix
Replace the failed coil (and inspect all six for blistering); most shops replace all six with spark plugs once the first fails past 80k miles. Use OEM Hitachi coils—aftermarket units have a poor reputation on this engine. If coils fail repeatedly, check engine grounds. No recall.
Sources for this issue (4)
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 Infiniti?
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 Infiniti it is documented across 1 model: G37.
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 Infiniti?
Published repair estimates on Infiniti range from $150 to $900 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.