When should spark plugs be replaced on a Toyota Highlander?

Most modern Toyota Highlanders use long-life, iridium- or platinum-tipped spark plugs designed for replacement intervals around 100,000 to 120,000 miles. Always verify the exact figure in the owner’s manual or with a Toyota dealer for your specific engine and model year.

Replacement timing varies with engine type, plug material, and driving conditions. This article outlines typical intervals by engine and plug type, common warning signs that plugs may be worn, and practical guidance on scheduling service.

Typical replacement intervals by engine and plug type

Because spark plug life depends on the plug material and how the Highlander is used, the following ranges reflect common guidance from Toyota and automotive service literature. The exact interval for your vehicle should come from your owner’s manual or your dealer.

• Copper-core spark plugs: about 60,000 miles under normal driving conditions.


• Platinum- or iridium-tipped spark plugs: typically 100,000 to 120,000 miles in normal use.


• Severe service (frequent short trips, heavy tows, extreme temperatures, or lots of stop-and-go driving): shorter intervals, often around 60,000 miles or sooner.

Bottom line: if your Highlander uses newer iridium or platinum plugs, plan for roughly a 100,000–120,000 mile change, but verify with the manual and consider conditions that might shorten that window.

Is it time to replace? Common signs your spark plugs are worn

Beyond the mileage clock, several telltale symptoms can indicate worn spark plugs on a Highlander. A pre-emptive check is wise if you notice any of these issues during routine driving.

• Rough idling or engine misfires, especially at idle or during acceleration.


• Reduced fuel efficiency and weaker acceleration.


• Hard or extended cranking when starting the engine.


• Engine pinging or knocking under load, or a check engine light that may indicate misfire codes.


• Unusual fuel smell or visible fouling on spark plug boots during inspection.

If you notice several of these symptoms, or if the vehicle is approaching the typical replacement window for your plug type, have a professional inspect the plugs and perform a diagnostic check.

How to approach replacement: DIY vs. professional service

Replacing spark plugs on a Highlander is a manageable task for many DIY enthusiasts with the right tools and torque specs, but it can be tricky on some engine layouts or hybrids. If you’re not comfortable with spark plug work, or if you have a turbo or hybrid engine with special service procedures, it’s wise to book a service appointment.

Regardless of who performs the work, ensure you use the correct plug type and torque specification, replace the end seals or boots if needed, and reset any maintenance reminders after replacement.

What to expect from the replacement service

Typical spark plug replacement involves removing the ignition coils or access covers, extracting old plugs without damaging threads, seating new plugs to the proper torque, and testing the engine for smooth operation. A reputable shop will also inspect ignition coils, ignition wires (if applicable), and related sensors as part of a standard tune-up when plugs are replaced.

How to confirm the exact interval for your Highlander

To obtain the precise replacement interval for your vehicle, consult the owner’s manual, check the maintenance schedule label on the driver’s door jamb, and ask your Toyota dealer or a qualified mechanic. Some Highlander models also show a maintenance minder alert when service is due, which can be a helpful guide beyond mileage alone.

Summary

For most modern Toyota Highlanders, spark plugs are designed for long life. Plan around a replacement window of roughly 100,000 to 120,000 miles for iridium or platinum plugs, with shorter intervals if you drive in severe conditions or still use older copper plugs. Watch for symptoms such as rough idling, reduced fuel economy, hard starting, or misfires, and verify the exact interval in the owner’s manual. When in doubt, rely on your dealership or a trusted mechanic to confirm the right schedule for your specific trim and year.

How long do Toyota Highlander spark plugs last?

Every 144 months/120,000 miles:
Regardless of which engine you have, you'll want to replace your spark plugs at this 12-year/120,000-mile mark.

How much does it cost to replace spark plugs in a Toyota Highlander?

The cost to replace the spark plugs in a Toyota Highlander varies by model year, engine type, and service location, but typically ranges from $340 to over $1,100. Hybrid and 4-cylinder engines are generally less expensive to service, while V6 models can cost more due to the complex labor involved, with quotes often exceeding $1,000 at dealerships for some V6 engines. 
Cost breakdown by factors

• Model Year and Engine Type:
  • V6 Engines: On some older V6 models, the cost can be much higher due to the labor-intensive process of removing the intake manifold and other parts to access the rear spark plugs. Prices for a 2008 V6 have been quoted between $1,080 and $1,475, while a 2017 V6 also received a quote of over $1,000, reports Torque News and Reddit. 
  • Hybrid and 4-Cylinder Engines: These models are generally less expensive. A 2020 hybrid was quoted between $415 and $575, and a 2012 4-cylinder was quoted between $340 and $455, according to YourMechanic and Kelley Blue Book. 
• Service Location:
  • Dealership: Dealerships typically use manufacturer-recommended parts and have highly trained technicians. This can lead to higher prices, with some quotes for V6 models exceeding $1,000, notes Kelley Blue Book and Reddit users. 
  • Independent/Mechanic Shops: These shops may use a wider range of parts, including aftermarket options, which can result in lower labor costs compared to a dealership. Quotes for a 2020 Highlander were around $415 to $490, notes Kelley Blue Book. 
• Parts: The cost of the spark plugs themselves depends on the type of plug the vehicle requires, such as iridium or platinum. For a set of plugs, the cost can range from about $50 to over $100, depending on the brand and material, as seen on sites like Walmart and AutoZone. 

What to consider

• Labor Intensive: On many Highlander models, particularly the V6, the spark plugs are located under the intake manifold. This requires significant labor to remove and reassemble, which is often the most expensive part of the job, says Torque News and {Link: Reddit users https://www.reddit.com/

How long do factory Toyota spark plugs last?

They usually last around 80,000 miles and are typically changed during routine, regularly scheduled maintenance according to the manufacturer's recommendations. Still, spark plugs can go bad, necessitating early replacement, so it's important to watch for signs of a malfunctioning or misfiring spark plug.

What year to stay away from a Toyota Highlander?

Years to avoid in the Toyota Highlander include 2003, 2008, 2014, 2015, and 2020 due to common issues like transmission problems, oil leaks, and technology glitches. Other problematic years to consider are 2001-2007 (engine and climate control issues) and 2016-2019 (varying issues including potential oil leaks in some models).
 
This video discusses problems with the Toyota Highlander from 2020 to 2025, including paint issues: 54sCarnivautoYouTube · Feb 11, 2025
Toyota Highlander years to avoid

• 2001–2007: Prone to engine overheating, head gasket failures, and climate control issues like AC compressor and blower motor problems. 
• 2003: A big year for issues, particularly engine oil sludge buildup and premature transmission wear, according to Regan Motors Inc and Clutch. 
• 2008: A redesigned model that experienced oil cooler line leaks, which can cause engine damage if not addressed, and lower-quality interior components. 
• 2014: A recall was issued for the second-row seat assembly that may not lock correctly into the seat track, and there were also reports of issues that might be linked to the transmission, says Clutch and Reddit users. 
• 2015: Experienced growing pains from its redesign, with various reports of growing issues, according to Regan Motors Inc and Clutch. 
• 2020: Experienced early transmission and software problems, say Clutch and Reddit users. 

You can watch this video to learn more about common problems with the 2020-2025 Toyota Highlander: 51sChris DrivesYouTube · Jul 5, 2025