A Guide to Spark Plugs for the 2019-2024 Toyota Highlander
Understand when to replace your spark plugs and how to choose the right aftermarket options for your Highlander's engine.
- For best results, use OEM-equivalent iridium spark plugs from Denso or NGK.
- The 3.5L V6 engine requires spark plug replacement every 60,000 miles, and the job is labor-intensive.
- Symptoms of failure include rough idle, poor acceleration, and a flashing check engine light.
- Always replace spark plugs as a full set and ensure they are torqued to the correct specification to avoid issues.
Signs of Failing Spark Plugs in Your Highlander
When spark plugs wear out, they can cause noticeable problems. You might experience one or more of these symptoms. Ignoring them can sometimes lead to more expensive repairs, like damage to ignition coils or catalytic converters.
- Rough Idle: Your engine may shake or vibrate more than usual when you're stopped at a light.
- Trouble Starting: The engine may take longer to start, or you might have to try several times.
- Poor Acceleration: Your Highlander might feel sluggish or slow to respond when you press the gas pedal.
- Worse Fuel Economy: You may find yourself filling up the gas tank more often than you used to.
- Check Engine Light: A failing spark plug can cause an engine misfire, which will trigger the check engine light. Common codes include P0300 (random misfire) or P0301-P0306 (for specific cylinders).
A Note on Loose Spark Plugs
Some Toyota owners have reported finding loose spark plugs from the factory. This can cause a rough idle and, in severe cases, damage the threads in the cylinder head, leading to a very expensive repair. When replacing plugs, it's critical to tighten them to the correct torque specification (around 13 ft-lbs for many Toyota engines).
Choosing the Right Aftermarket Spark Plugs
Your Highlander came from the factory with high-quality iridium spark plugs, most likely made by Denso or NGK. These two brands are the original equipment (OEM) suppliers for Toyota. For the best performance and reliability, sticking with these brands is a smart choice. Aftermarket plugs from Denso and NGK are often identical to the parts sold at a Toyota dealership, just in different packaging.
Brand Quality Tiers for Toyota Highlander
- Tier 1 (OEM Equivalent): Denso and NGK. These are the top recommendation for a direct, reliable replacement. They are designed for long life and optimal performance in your Highlander's specific engine. Be aware of counterfeit plugs sold online; it's safest to buy from reputable auto parts suppliers.
- Tier 2 (Reputable Aftermarket): Bosch and Champion. These brands also produce quality iridium and platinum plugs that are suitable replacements. While not the OEM supplier, they are well-known manufacturers with a long history.
- Tier 3 (Budget): Autolite. This brand often offers a more budget-friendly option. While functional, they may not offer the same longevity or precise performance as the OEM-equivalent brands. For a vehicle like the Highlander, especially the V6 where replacement is labor-intensive, investing in Tier 1 plugs is highly recommended to avoid doing the job again sooner.
When to Replace Your Spark Plugs
The replacement interval depends on your engine. For the 3.5L V6 engine (2019-2022 models), Toyota recommends replacing the spark plugs every 60,000 miles. For other engines and newer models with the 2.4L Turbo, the interval is typically longer, around 80,000 to 120,000 miles. Always check your owner's manual for the specific schedule for your vehicle. Driving in harsh conditions like frequent stop-and-go traffic may require you to replace them sooner.
Cost of Spark Plug Replacement (2019-2024 Highlander)
| Item | Estimated Cost |
|---|---|
| New Aftermarket Spark Plugs (Set of 4 or 6) | $40 - $200 |
| Shop Labor | $250 - $600+ |
| Total Estimated Cost | $290 - $800+ |
Note: Labor costs for the V6 engine are significantly higher because the intake manifold must be removed to access the rear three spark plugs, a process that can take 2-3 hours for an experienced mechanic.
Frequently Asked Questions
What's the difference between Iridium and Platinum plugs?
Iridium is a harder, more durable material than platinum. Modern engines like the one in your Highlander are designed for iridium plugs, which last longer (up to 120,000 miles in some cases) and provide a more consistent spark over their lifespan. Platinum plugs are also a good long-life option, but iridium is the superior, factory-specified technology for your vehicle.
Do I need to gap the spark plugs before installing them?
Most modern iridium plugs from brands like Denso and NGK come pre-gapped from the factory. While it's a good practice to gently check the gap with a proper tool, you should not attempt to adjust the gap on a fine-wire iridium plug, as you can easily break the delicate electrode. If the gap is incorrect, it's better to return the plug for a new one.
Can I replace just one bad spark plug?
It's strongly recommended to replace all spark plugs at the same time. They wear at a similar rate, so if one has failed, the others are likely near the end of their service life. Replacing them all at once ensures balanced engine performance and saves you from having to do the job again in the near future.
Is this a DIY job?
For the 3.5L V6 engine, this is a difficult DIY job. Accessing the rear bank of spark plugs requires removing the upper intake manifold. This is a 2-4 hour job that requires care and the right tools. For the 4-cylinder engine, the job is much simpler and is feasible for a DIYer with basic tools. If you are not comfortable with more involved engine work, it's best to leave the V6 replacement to a professional.
Helpful Videos
Technical Specifications
OEM Part Numbers: 90919-01263 90919-A1008 90919-01289
The 2019-2022 Highlander with the 3.5L V6 (2GR-FKS engine) requires 6 spark plugs. The 2023-2024 models with the 2.4L Turbo I4 (T24A-FTS engine) require 4 spark plugs. Both engines use long-life iridium-tipped spark plugs.
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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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- Signs of Failing Spark Plugs in Your Highlander
- A Note on Loose Spark Plugs
- Choosing the Right Aftermarket Spark Plugs
- Brand Quality Tiers for Toyota Highlander
- When to Replace Your Spark Plugs
- Cost of Spark Plug Replacement (2019-2024 Highlander)
- Frequently Asked Questions
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