DENSO Auto Parts Iridium Spark Plug 3421
Part #
3421
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quantity
Specifications:
Part Number:
SKU Number:
Ground Electrode Tip Material:
Resistor Type:
Features:
- Iridium is 6x harder and 8x stronger than platinum
- Iridium reduces oxidation, increasing longevity
- Iridium alloy melting point over 4,000 degrees
| Part # | 3421 |
|---|---|
| SKU # | 533116 |
| Ground Electrode Tip Material | Platinum |
| Resistor Type | Yes |
| Center Electrode Tip Material | Iridium |
| Pre-Gap Size | 1.1mm |
| Center Electrode Core Material | Copper |
| Grade Type | Standard Replacement |
| Seat Type | Flat |
| Reach | 26.5mm |
| Manufacturer Heat Range | 20 |
| Metal Type | Iridium |
| Ground Electrode Tip Design | Platinum Chip |
| Ground Electrode Quantity | 1 |
| Ground Configuration | Standard |
| Ground Electrode Core Material | Nickel |
Manufactured to the strictest OE performance, durability and emissions standards.
- DENSO patented optimized iridium-rhodium alloy formula: highest concentration of iridium vs competitors for greater durability
- Extra long life spark plugs manufactured to OEM service interval specifications
- OE style iridium with iridium alloy center electrode (90% Ir) & platinum ground strap
- DENSO patented 360 degree laser welding process: ensuring exceptional quality bond and structural strength with the iridium center electrode
Spark Plugs Metal Types
Currently Viewing  DENSO Auto Parts Iridium Spark Plug 3421 | ||||
|---|---|---|---|---|
Customer Rating | - | (1)Total Reviews | (3)Total Reviews | (1)Total Reviews |
Price | Total price is: 13 dollars and 99 cents. | Total price is: 9 dollars and 99 cents. | Total price is: 12 dollars and 99 cents. | Total price is: 5 dollars and 99 cents. |
Metal Type | Iridium | Iridium | Iridium | Platinum |
78 Ratings
95% Recommended
Customer Media
Review Summary
Customers overwhelmingly praise these iridium spark plugs as exact OEM replacements that restore engine performance and deliver exceptional durability. Most highlight seamless installation, improved fuel efficiency, and engines running like new after replacement. Many report fuel economy gains from 13-14 MPG to 18-20 MPG, eliminated misfires, and smoother throttle response. Reviewers consistently note the pre-gapped design requires no adjustment, enabling quick, hassle-free installation. Several customers report original plugs lasting over 100,000 miles and repurchase confidently. A few mention price concerns or isolated longevity issues, but these are vastly outweighed by widespread satisfaction and strong recommendations.
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66 Reviews
Great plugs, great price, good for BMW
ANTHONY1 month agoRecommendedReplaced in 2011 bmw 528i. Noticeable increase in response. Car runs nice and is operating great. Good products at a good price. Ngk is great and these are goodPurchased for: 2011 BMW 528iHelpful?
Met expectations
James1 month agoVerified PurchaseRecommendedWorked as expectedPurchased for: BMW 3 seriesHelpful?
- JON2 months agoVerified PurchaseRecommendedGood Quality Part.Purchased for: 2007 Toyota Tacoma
Helpful?
Good spark plugs
Chief2 months agoVerified PurchaseRecommendedSpark plugs worked well in my BMW 528i. Pre gapped before installing and engine us purring luke a kitten now. I highly recommendPurchased for: 2011 BMW 528iHelpful?
Denso is the way to go for all FJ Cruisers!
ACE2 months agoVerified PurchaseRecommendedMade a significant change in my vehicles idle and gas performance! My AutoZone Rep Howard in San Antonio on Potranco #3532 was awesome and recommended Denso as the premier plug for my FJ Cruiser!Purchased for: 2008 Toyota FJ CruiserHelpful?
Routine maintenance
JASON3 months agoVerified PurchaseProduct is working great.Helpful?
Plugged
Nicolas3 months agoVerified PurchaseRecommendedPerfect fit thanksHelpful?
- KEITH4 months agoVerified PurchaseRecommendedExcellent PlugsPurchased for: 2005 Toyota 4Runner 4WD 6 Cylinders U 4.0L FI DOHC 245 CID
Helpful?
Spark away
Mike5 months agoVerified PurchaseRecommendedGood brand. Very reliable.Purchased for: 2017 toyota tundraHelpful?
Denso Spark Plugs
Gc5 months agoVerified PurchaseWorks good and fits just rightHelpful?
Good
Frank6 months agoVerified PurchaseRecommendedNeeded a tune up badHelpful?
Denso has overall good quality.
Jay Montemayor6 months agoVerified PurchaseRecommendedThese were used on a 2018 Toyota Tundra (4.6L); the truck did not have a miss prior but still needed to change the plugs as the old ones had reached 75k miles. These new Iridiums seem to make it spud just a little bit, not bad but maybe they just need to be broken in. I know that these spark plugs in many markets can be counterfeits but I really hope AZ does not carry any.Purchased for: 2018 Toyota Tundra SR (4.6L)Helpful?
New Denso Spark Plugs.
Anonymous7 months agoVerified PurchaseRecommendedSo far so good. I wish they were little cheaper.Purchased for: It was for a Toyota Sequoia.Helpful?
No issues
Iridium or go home7 months agoVerified PurchaseRecommendedExact replacementPurchased for: 12 tacomaHelpful?
Dependable quality from Denso
Anonymous8 months agoVerified PurchaseInstalled on 2016 Ducati multistrada 1200s and works as expected. Always a good product from Denso.Purchased for: 2016 Ducati multistrada 1200s DVTHelpful?
Great in the Tundra
Danno9 months agoVerified PurchaseRecommendedI used these in my Tundra as they are the OEM plugs. I am very happy with the results and I will order them again when needed.Purchased for: 2014 Toyota TundraHelpful?
OEM 5.7 Tundra
KV9 months agoVerified PurchaseRecommendedPurchased these for my 21 Tundra 5.7 because they're oem.Purchased for: 2021 Toyota Tundra Crewmax Sr5 5.7Helpful?
Spark plugs work excellent
Raphael10 months agoVerified PurchaseRecommendedMY 2009 328I XDRIVEPurchased for: 2009 BMW 328I XDRIVE SEDANHelpful?
Easy
Shea W10 months agoVerified PurchaseRecommendedDidn’t have to gap and there was a noticeable increase in pedal response!Purchased for: 2016 Tundra 4x4 4.6LHelpful?
OEM toyota plugs
herny10 months agoVerified PurchaseRecommendedThese are the oem spark plugs for a 2010 tundra 5.7, they shot my mpgs from 13-14 back up to 18-20 mpg as i was riding on the originals at 130k milesPurchased for: 2010 Tundra RCSB 5.7Helpful?
Advice and How-To's
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