P0306 on Infiniti: How to Diagnose & Fix
Cylinder 6 Misfire Detected
1 Infiniti model · 1 documented issue · $150-$900 repair
P0306 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 bulletin ITB11-017A, written for the FX35 (not the G37), ties P0300-P0306 misfires and blistered coils to poor engine grounds and battery cables, and owners and parts guides apply the same logic to the G37. On the G37 the coils are reached by removing the engine cover, airbox, intake tube and moving the throttle body aside; the middle coil on each bank is the hardest to get to.
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 (6)
- p0300 missfire on g37 - MyG37forum
- P0300 & P0303 codes, No relief in sight - MyG37forum
- P0300 Random Multiple misfire - NICOclubforum
- P0300 on 2008-2013 Infiniti G37: Random Misfire Causes and Fixes (references ITB11-017A)article
- Infiniti ITB11-017A - Blistered ignition coils with misfire DTC (FX35)tsb
- How to Replace Ignition Coils 2008-2013 Infiniti G37 3.7L V6 - 1A Autoarticle
P0306 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 P0306 mean on a Infiniti?
P0306 stands for "Cylinder 6 Misfire Detected." This code means the engine computer detected a misfire on cylinder 6 — that cylinder isn't burning its fuel-air mixture properly. The computer senses misfires by watching for tiny variations in crankshaft speed each time a cylinder should fire, and when cylinder 6 repeatedly fails to contribute, this code sets. You may feel a shake or stumble, especially at idle or under load, along with reduced power and possibly a flashing check-engine light, which signals a misfire severe enough to damage the catalytic converter. A misfire comes down to a problem with spark, fuel, or compression in that cylinder. On Infiniti it is documented across 1 model: G37.
What are the most common causes of P0306?
The most common causes of P0306 are: Worn or fouled spark plug on cylinder 6, Failed ignition coil for cylinder 6, Clogged, leaking, or failed fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt valve, head gasket), Damaged plug wire or coil connector, Carbon buildup or worn valvetrain components. The specific cause varies by vehicle.
How much does it cost to fix P0306 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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.