Denso SK20HR11 iridium platinum spark plugs – close-up showing durable tip design for smoother starts.
Denso spark plug 3421 four-pack — packaging photo highlighting a ready-to-install set.
Denso SK20HR11 iridium platinum spark plugs – close-up showing durable tip design for smoother starts.
Denso spark plug 3421 four-pack — packaging photo highlighting a ready-to-install set.

Denso SK20HR11 Iridium Platinum Spark Plugs – 4-Pack 3421 (Genuine Denso)

OverviewDiscover the DENSO SK20HR11 Iridium Platinum spark plugs, a genuine four-pack designed to support reliable ignition in...
Vendor: Denso
Availability: In stock
£55.23
£55.23
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Subtotal: £55.23
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Denso SK20HR11 iridium platinum spark plugs – close-up showing durable tip design for smoother starts.

Denso SK20HR11 Iridium Platinum Spark Plugs – 4-Pack 3421 (Genuine Denso)

£55.23
Denso SK20HR11 iridium platinum spark plugs – close-up showing durable tip design for smoother starts.
Denso spark plug 3421 four-pack — packaging photo highlighting a ready-to-install set.

Denso SK20HR11 Iridium Platinum Spark Plugs – 4-Pack 3421 (Genuine Denso)

£55.23
Description
Description
x

Overview

Discover the DENSO SK20HR11 Iridium Platinum spark plugs, a genuine four-pack designed to support reliable ignition in everyday driving. The SK20HR11 uses a durable iridium-platinum alloy to resist wear, helping maintain a strong, consistent spark across miles. Cataloged as 3421, these plugs align with a wide range of compatible engines, offering trusted performance from a brand you can rely on.

What you get: A convenient four-piece set that simplifies maintenance planning. This item ships free within the United States and territories, making it easy to stock up for future service without extra shipping costs.

Why drivers consider this set

  • Genuine DENSO 3421 spark plugs with brand backing
  • Iridium-platinum electrode design for high durability and consistent sparking
  • 4-piece pack supports full replacement in one service
  • Free shipping to USA and territories with this item

Real-life use cases

Whether you are prepping for a seasonal tune-up, replacing worn plugs in an older vehicle, or updating a fleet maintenance schedule, this 4-pack makes it easier to refresh ignition performance without placing multiple orders.

Performance notes: results can vary by vehicle, but many users report smoother starts, quicker warm-up, and more stable idle when plugs are in good condition. The iridium-platinum tips are designed to resist wear over time, potentially reducing misfires and improving reliability in some cases.

Installation tips

  • Consult your vehicle manual for torque specs and follow recommended procedures
  • Handle plugs carefully to avoid damaging electrode tips
  • Use manufacturer guidance for thread lubrication or anti-seize where advised

In short, the DENSO 3421 four-pack offers a trusted brand, a robust material build, and the convenience of bulk packaging for easier maintenance planning.

FAQ

Q: What’s included in this DENSO 3421 four-pack?

A: A genuine four-pack of SK20HR11 spark plugs, model 3421, ready for installation.

Q: Does this item qualify for free shipping?

A: Yes, free shipping is offered to the USA and territories for this item.

Shipping & Return
Shipping & Return
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Returns Policy

You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Shipping

We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

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