A Guide to Spark Plugs for the 2004-2013 Infiniti QX56
Keep your QX56's 5.6L V8 engine running strong by understanding its spark plug needs.
- For best performance and longevity, use OEM-equivalent Iridium spark plugs from brands like NGK or Denso.
- Symptoms of failure include rough idle, poor acceleration, reduced fuel economy, and a check engine light with P0300-series codes.
- While a DIY-friendly job, replacing the plugs requires a special 14mm thin-wall socket and patience for the rear cylinders.
- Always verify the spark plug gap is correct (typically 0.043") before installation to prevent misfires.
Symptoms of Failing Spark Plugs
When your spark plugs start to wear out, your QX56 will give you several warning signs. Because worn plugs can't ignite the fuel mixture efficiently, you may experience a range of performance issues. Ignoring these symptoms can lead to reduced fuel economy and potentially more expensive engine problems down the road.
- Rough Idle: The engine may shake or vibrate more than usual when stopped.
- Engine Misfires: You might feel a hesitation or stumbling during acceleration. A blinking check engine light is a serious sign of a misfire.
- Poor Acceleration: The vehicle may feel sluggish and less responsive than normal.
- Reduced Fuel Economy: Worn spark plugs can cause a significant drop in gas mileage, sometimes by as much as 30%.
- Difficulty Starting: A weak spark can make it harder for the engine to turn over, especially in cold weather.
- Check Engine Light: A common trouble code for spark plug issues is P0300 (Random/Multiple Cylinder Misfire 🎬 Watch this video to understand and fix P0300 misfire codes.) or codes P0301 through P0308, which point to a misfire in a specific cylinder.
Choosing the Right Aftermarket Spark Plugs
When shopping for new spark plugs for your 2004-2013 QX56, you'll find several types and brands. The original equipment manufacturer (OEM) for Infiniti is typically NGK, and the factory-installed plugs are long-lasting Iridium types. For a direct-fit replacement that maintains factory performance and longevity, choosing an Iridium plug from an OEM-equivalent brand is your best bet.
Brand & Material Quality Tiers
| Tier | Brands | Material | Typical Lifespan | Notes |
|---|---|---|---|---|
| Top Tier / OEM Equivalent | NGK, Denso | Iridium | ~100,000 miles | These brands are often the original equipment suppliers. They offer the best performance and longest life, matching the factory plugs. The OEM NGK plug for many QX56 models is an Iridium/Platinum hybrid. |
| High-Quality Aftermarket | Bosch | Double Iridium, Double Platinum | 60,000-100,000 miles | Bosch offers excellent Iridium and Platinum plugs that are a reliable alternative to NGK and Denso, often at a competitive price. |
| Standard / Budget | Autolite, Champion | Platinum, Copper | ~30,000 miles | While functional, these plugs generally have a much shorter service life than Iridium plugs. They are a cost-effective option but will require more frequent replacement. |
Pro Tip: For the best results and to maintain the original performance characteristics of your QX56, stick with Iridium spark plugs from NGK or Denso. While cheaper copper or platinum plugs will work, they won't last as long and may not provide the same level of performance as the factory-specified plugs.
Known Issues, Recalls, and TSBs
While there are no specific recalls or technical service bulletins (TSBs) directly for spark plugs on the 2004-2013 QX56, related issues can cause similar symptoms. An important recall for 2004-2006 models involved the Engine Control Module (ECM) relay, which could fail and cause engine stalling, a symptom sometimes mistaken for bad spark plugs. Additionally, some 2011-2013 models were part of a voluntary service campaign to replace timing chains, which can also cause performance issues if they fail. When diagnosing a misfire, it's important to consider these other possibilities if new spark plugs don't solve the problem.
Frequently Asked Questions (FAQ)
How often should I replace the spark plugs on my QX56?
If you use the OEM-recommended Iridium spark plugs, the replacement interval is typically around 100,000 miles. However, some sources suggest a more frequent interval of 30,000 km (approx. 18,600 miles), which may apply to standard copper plugs. Always check your owner's manual for the specific recommendation for your vehicle.
What tools do I need to change the spark plugs?
You will need a ratchet, several extensions of different lengths, a 10mm socket for the ignition coil bolts, and a special 14mm thin-wall spark plug socket. A swivel socket and a magnetic tool to retrieve the old plugs can also be very helpful, especially for the harder-to-reach cylinders.
Is replacing the spark plugs a DIY job?
Yes, for many owners with basic mechanical skills, this is a feasible DIY job. The passenger-side plugs are generally easy to access, but the driver's side can be more challenging due to components being in the way. Be patient, especially with the rearmost plugs near the firewall. One common issue is the ignition coil boot sticking to the old spark plug 🎬 See how to handle a stuck ignition coil boot., which may require careful effort to remove.
Should I check the gap on new spark plugs?
Yes. While most high-quality Iridium plugs come pre-gapped, it's always a good practice to verify the gap before installation. The recommended gap for many QX56 models is 0.043 inches (1.1mm). Dropping a plug can close the gap, which will cause a misfire.
Should I also replace the ignition coils with the spark plugs?
It is not required, but it is often recommended. The ignition coils sit directly on top of the spark plugs and must be removed to access them. If your vehicle has high mileage, replacing the coils at the same time as the plugs can be a good preventative measure to avoid having to do the labor twice if a coil fails 🎬 Follow this step-by-step guide to replace your plugs and coils. soon after.
Helpful Videos
Technical Specifications
OEM Part Numbers: 22401-ZE01B 22401-5M015 22401-5M016 22401-1LA1C
Socket Size: 14mm Thin Wall Gap: 0.043" (1.1mm) OEM Material: Iridium/Platinum Torque Spec: ~18 ft-lbs
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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.
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