Spark Plug Replacement Guide for the 2006-2015 Lexus IS250
Keep your IS250's V6 engine running smoothly with the right spark plugs.
- Stick to Denso or NGK iridium spark plugs for OEM-level performance and longevity.
- Replacement is recommended every 60,000 miles as per the Lexus maintenance schedule.
- The job is complex for DIYers, as it requires removing the intake manifold to access all six plugs.
- Always replace the intake manifold gaskets when doing this job to avoid vacuum leaks.
Signs of Failing Spark Plugs in Your IS250
When spark plugs start to wear out, your Lexus will give you several warning signs. A common symptom is a rough idle or the engine shaking at a stop. You might also notice the "Check Engine" light comes on, often with codes indicating an engine misfire (P0300-P0306). Other signs include a noticeable drop in fuel economy, slower acceleration, and difficulty starting the engine. In some cases, the "TRAC OFF" light may also illuminate alongside the Check Engine light when a misfire is detected.
Choosing the Right Aftermarket Spark Plugs
For the 2006-2015 Lexus IS250, the original equipment (OEM) spark plugs were made by Denso. When choosing replacements, sticking with OEM-equivalent quality is highly recommended by both mechanics and owners.
Spark Plug Brand Tiers for Lexus IS250
| Tier | Brands | Quality & Performance Notes |
|---|---|---|
| OEM Equivalent / Top Tier | Denso, NGK | Both Denso and NGK are original equipment suppliers for Toyota and Lexus. They offer Iridium and Double Iridium plugs that provide long life and performance consistent with factory standards. The Denso FK20HBR11 and NGK Laser Iridium are highly recommended choices. You can expect 60,000 to 100,000 miles of service from these plugs. |
| Quality Aftermarket | Bosch, Champion | Bosch and Champion offer Iridium and Double Platinum plugs that are a good alternative to the top-tier brands. They provide reliable performance and are often a more budget-friendly option while still offering good longevity. |
| Economy / Standard | Autolite | Autolite offers a range of plugs from basic copper to platinum and iridium. While functional, their copper plugs will have a much shorter service life and are not recommended for the IS250's engine, which was designed for long-life iridium plugs. Their iridium options are a viable budget choice, but may not match the lifespan of Denso or NGK. |
A Note on Counterfeit Parts: Be extremely cautious when purchasing Denso or NGK spark plugs from online marketplaces like Amazon or eBay. Counterfeit plugs are common and can cause poor performance, misfires, and even engine damage. It is safest to buy from reputable auto parts stores or a trusted dealer.
Known Issues, Recalls, and TSBs
There are no specific recalls or Technical Service Bulletins (TSBs) from Lexus or the NHTSA directly related to spark plugs for the 2006-2015 IS250. However, the 4GR-FSE engine is known for issues with carbon buildup on the intake valves due to its direct injection design. While not a spark plug problem, severe carbon buildup can affect combustion and lead to symptoms similar to failing plugs, such as rough idle and misfires.
🎬 Learn how to walnut blast intake valves to clear carbon buildup.Frequently Asked Questions (FAQ)
How often should I change the spark plugs on my IS250?
The Lexus scheduled maintenance guide recommends replacing the spark plugs every 60,000 miles. While modern iridium plugs can last longer, following this interval is the best way to ensure optimal engine performance and prevent issues.
Is it difficult to replace the spark plugs myself?
The job is more complex than on many other cars. The passenger-side plugs are relatively easy to access, but reaching the driver-side plugs requires removing the upper intake manifold and throttle body. This makes the job moderately difficult for a DIY mechanic and requires specific tools like a 5mm Allen socket 🎬 Watch this detailed step-by-step guide for the full replacement process. and a torque wrench. It is estimated to take a professional about 1.5 to 2.5 hours.
Should I use anti-seize on the new spark plugs?
Yes, it is recommended to apply a small amount of nickel-based anti-seize lubricant to the threads of the new spark plugs. This prevents them from getting stuck in the cylinder head, making future replacement easier. Also, apply a small amount of dielectric grease to the inside of the ignition coil boot to protect it and ensure a good connection.
Do I need to gap the new spark plugs?
No. High-quality iridium plugs from brands like Denso and NGK come pre-gapped from the factory for your specific vehicle. You should not attempt to gap them, as you can easily damage the fine iridium tip.
What other parts should I replace at the same time?
When you remove the intake manifold, it is highly recommended to replace the intake manifold gaskets to prevent vacuum leaks. It's also a good idea to have new fuel line crush washers on hand if you disconnect the fuel line. Many of the plastic electrical connectors can become brittle with age and may break when disconnected; be prepared for this possibility.
🎬 See how to handle and replace those brittle electrical connectors.Helpful Videos
Technical Specifications
OEM Part Numbers: 90919-01249 FK20HBR11
Engine: 2.5L V6 (4GR-FSE). Quantity required: 6. Recommended Type: Iridium. Torque Spec: 18 ft-lbs. Spark Plug Socket Size: 5/8 inch.
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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.
- Lexus IS250: