P0302 on Infiniti: How to Diagnose & Fix
Cylinder 2 Misfire Detected
1 Infiniti model · 1 documented issue · $150-$900 repair
P0302 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)
P0302 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 P0302 mean on a Infiniti?
P0302 stands for "Cylinder 2 Misfire Detected." This code means the engine computer has detected a misfire specifically in cylinder 2, meaning that cylinder isn't completing combustion properly on some firing events. The computer watches tiny variations in crankshaft speed to spot when a cylinder fails to fire, and a misfire means the air-fuel mixture isn't igniting correctly — usually from a spark, fuel, or compression problem in that cylinder. You may feel a stumble, rough idle, shaking, loss of power, or a flashing check-engine light, and persistent misfires can damage the catalytic converter. Because it names a single cylinder, the fault is often a component serving just cylinder 2, like its coil, plug, or injector. On Infiniti it is documented across 1 model: G37.
What are the most common causes of P0302?
The most common causes of P0302 are: Worn or fouled spark plug (cylinder 2), Failed ignition coil or coil-on-plug (cylinder 2), Clogged or faulty fuel injector (cylinder 2), Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/bent valve, head gasket), Damaged spark plug wire or boot (if equipped), Carbon-tracked or cracked coil/plug causing spark loss, Faulty PCM/ECM driver (rare). The specific cause varies by vehicle.
How much does it cost to fix P0302 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 P0302 on a different make?
View P0302 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.