A Comprehensive Guide to Spark Plugs for the 2011-2012 Infiniti G25
Everything you need to know before replacing the spark plugs on your G25's VQ25HR engine.
- Stick with iridium spark plugs to match the original factory equipment; NGK is the OEM supplier and the most recommended brand.
- Symptoms of failure include a rough idle, poor gas mileage, engine hesitation, and a check engine light with P0300-series misfire codes.
- High-quality aftermarket plugs come pre-gapped; do not attempt to adjust the gap on fine-wire iridium plugs.
- Always replace all six spark plugs at once to ensure balanced engine operation and performance.
Function and Failure
The spark plugs in your 2011-2012 Infiniti G25 are responsible for igniting the air-fuel mixture inside the engine's combustion chambers. Your G25 came from the factory with long-life iridium spark plugs, designed to last for many thousands of miles. Over time, the electrodes on these plugs wear down, which can lead to a weaker spark. This results in incomplete fuel combustion, causing a noticeable decline in engine performance and fuel efficiency.
🎬 Watch: Common symptoms of worn out spark plugsDiagnosing a Misfire (P0300 Code)
While worn spark plugs are a very common reason for a Check Engine Light with a P0300 (random misfire) or P0301-P0306 code, they are not the only cause. Other potential issues include faulty ignition coils, vacuum leaks, or fuel delivery problems. It is important to diagnose the problem correctly before replacing parts.
🎬 See how to diagnose misfires in hard-to-reach cylindersChoosing the Right Aftermarket Spark Plug
When replacing the spark plugs in your G25, it is highly recommended to use new iridium plugs. This will maintain the performance and long service intervals your car was designed for. Using cheaper plug types like standard platinum or copper can lead to poor performance and will require you to change them much more frequently.
Brand Tiers for Your G25
- Tier 1 (OEM-Quality): NGK
NGK is the original equipment (OEM) supplier for Infiniti, meaning they made the plugs your car came with from the factory. Their Laser Iridium and Iridium IX series are considered the top choice and safest bet for the G25, ensuring perfect compatibility and performance. Mechanics at Infiniti dealerships use NGK plugs for service. - Tier 2 (Quality Aftermarket): Bosch
Bosch offers high-quality Double Iridium spark plugs that are a good alternative. While Bosch is a reputable brand known for excellent products, most mechanics and Infiniti enthusiasts stick with NGK for Japanese engines like the VQ25HR to guarantee compatibility. - Tier 3 (Functional): Champion
Champion also produces iridium spark plugs that fit the G25. They are a functional and often more budget-friendly option, but they are not as commonly recommended or used in Infiniti forums compared to NGK or Bosch for this specific vehicle.
| Brand Tier | Brand(s) | Price Range (Per Plug) | Notes |
|---|---|---|---|
| Tier 1 (OEM-Quality) | NGK | $9.50 - $20.00 | The original equipment supplier. The safest and most recommended choice. |
| Tier 2 (Quality Aftermarket) | Bosch | $9.00 - $16.00 | A reliable alternative, though NGK is generally preferred for this engine. |
| Tier 3 (Functional) | Champion | $8.00 - $12.00 | A functional, budget-conscious choice. |
Installation Tip
To access all six spark plugs on the VQ25HR engine, you will need to remove the engine cover and both throttle bodies. While this is a manageable DIY job for those with some experience, it is more involved than on many other engines. Always replace all six spark plugs at the same time for balanced engine performance.
🎬 Watch this step-by-step guide to replacing your spark plugsFrequently Asked Questions
How often should I replace the spark plugs on my G25?
The recommended replacement interval for the original iridium spark plugs is approximately every 105,000 miles. Using high-quality aftermarket iridium plugs should provide a similar lifespan.
Do I need to gap the new spark plugs?
No. High-quality iridium spark plugs from brands like NGK and Bosch come pre-gapped from the factory for your G25. It is strongly recommended *not* to adjust the gap, as you can easily damage the delicate fine-wire iridium tip.
Are there any recalls for the G25 spark plugs?
No, there have been no recalls or major technical service bulletins (TSBs) issued by Infiniti or the NHTSA for spark plug issues on the 2011-2012 G25.
Should I use anti-seize on the new spark plug threads?
This is a topic of debate, but modern NGK plugs often have a special plating that acts as its own anti-seize. Applying additional anti-seize can lead to over-torquing and can sometimes cause misfires if applied incorrectly. It is generally best to follow the plug manufacturer's specific instructions, which often advise against it.
Helpful Videos
Technical Specifications
OEM Part Numbers: 22401-EW61C
Hex Size: 14mm. Plug Type: Iridium. Quantity: 6 required.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Infiniti G25: