A Guide to Spark Plug Replacement for the 2008-2013 INFINITI G37
Keep your G37's VQ37VHR engine running smoothly with the right set of new spark plugs.
- Stick with OEM-equivalent Iridium spark plugs from Denso or NGK for the best performance and reliability on the G37's VQ37VHR engine.
- Always verify the spark plug gap is correct (around 0.044 inches) before installation, even if they are sold as pre-gapped.
- Replacement requires unbolting and moving the throttle bodies, making it a moderately difficult DIY job.
- Symptoms like a rough idle, misfires (P0300 codes), and poor fuel economy are strong indicators that your spark plugs need to be replaced.
Signs of Failing Spark Plugs in Your G37
When your G37's spark plugs start to wear out, you'll likely notice. The original factory plugs are designed to last a long time, often up to 100,000 miles, but failures can happen sooner. Look out for these common symptoms:
- Rough Idle: The engine may shake or vibrate noticeably when you're stopped.
- Engine Misfires: You might feel a hesitation or stumble during acceleration, often accompanied by a flashing Check Engine Light. This can trigger codes like P0300 (random misfire) or P0301-P0306 for specific cylinders.
- Reduced Power and Acceleration: Your G37 may feel sluggish and less responsive than usual.
- Worse Fuel Economy: Worn plugs are less efficient, which can lead to a noticeable drop in your gas mileage, sometimes by as much as 30%.
- Difficulty Starting: The engine may take longer to crank before it starts, especially in cold weather.
Check for Other Issues
While spark plugs are a common cause for misfires, other problems can show similar symptoms. A torn air intake boot or a faulty ignition coil can also cause a P0300 random misfire code. It's wise to inspect the air intake system for cracks and check the ignition coils for damage when you replace your plugs.
Choosing the Right Aftermarket Spark Plugs
For the INFINITI G37's VQ37VHR engine, selecting the right type of spark plug is essential for maintaining performance and reliability. The original equipment (OEM) plugs are made by Denso and are an Iridium-type plug. When shopping for aftermarket replacements, sticking with a high-quality Iridium plug is highly recommended by owners and mechanics.
Brand Quality Tiers
- OEM-Equivalent (Best Choice): Denso and NGK are the top choices for the G37. Denso is the original supplier, and their Iridium Long-Life plugs are a direct replacement. NGK Laser Iridium or Ruthenium plugs are also highly regarded by G37 owners and are considered an excellent alternative, sometimes preferred for modified engines. Many owners feel there is no better option than the OEM Denso plugs.
- Quality Aftermarket: Bosch offers Double Iridium plugs designed to meet or exceed OEM specifications. These are a reliable choice if Denso or NGK are not available.
- Standard/Economy: Brands like Champion or Autolite are generally not recommended for the G37's high-performance engine. While they are more affordable, owners report that the VQ engine performs best with the OEM-spec Iridium plugs it was designed for. Using a lower-quality plug could lead to performance issues.
Always Check the Gap
Even though many Iridium plugs come "pre-gapped," it's a crucial step to check the gap on each plug before installation. The correct gap for the G37 is typically 0.043 or 0.044 inches. A plug could have been dropped during shipping, altering the gap and potentially causing performance problems.
Cost of Replacing Spark Plugs on a 2008-2013 G37
| Part Type | Price Range (Set of 6) |
|---|---|
| New Aftermarket (Denso, NGK, Bosch) | $57 - $185 |
| New OEM (Infiniti-Branded Denso) | $120 - $185 |
| Shop Labor | $150 - $300 |
Prices are estimates and may vary based on location and parts supplier. Your G37 requires six spark plugs.
Frequently Asked Questions (FAQ)
Are there any recalls for the G37 spark plugs?
No, there are no specific recalls for the spark plugs on the 2008-2013 INFINITI G37. Searches of the NHTSA database did not show any recalls related to the ignition system or spark plugs for this vehicle.
How difficult is it to change the spark plugs myself?
The job is moderately difficult and feasible for a DIY mechanic with the right tools. You will need to remove the engine cover and the air intake ducts. To access all six plugs, the throttle bodies on both sides of the engine must be unbolted and moved aside, which requires a 5mm hex/Allen socket. This makes the job more involved than on simpler engines. New throttle body gaskets are recommended when you do this job.
Should I replace my ignition coils at the same time?
It is generally not necessary to replace ignition coils as a preventative maintenance item. Unlike spark plugs, coils are not a typical wear item and should only be replaced if they have failed, which would usually trigger a specific misfire code (e.g., P0301, P0302). However, if the car has high mileage (over 100k miles) and you are already paying for the labor, some owners choose to replace them for peace of mind.
What is the difference between Denso and NGK plugs for my G37?
Both are excellent Japanese brands that meet or exceed OEM requirements. Denso is the original equipment manufacturer for the G37. NGK is a very popular high-quality alternative. For daily driving, the performance difference is negligible, and you can confidently choose whichever is more cost-effective. Some enthusiasts prefer NGK for modified or high-performance applications.
Helpful Videos
Technical Specifications
OEM Part Numbers: 22401-JK01D
Material: Iridium, Quantity: 6, Recommended Gap: 0.044 in (1.1mm)
We Have This Part in Stock
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 G37: