Authenticity of DENSO Iridium TT

[Gannet167]

I bought DENSO Iridium TT plugs from RockAuto, part 4704, DENSO part IKH20TT. I am not overly impressed with the quality of them and have doubts about their authenticity. I emailed DENDO and they say RockAuto is not an authorized dealer. Seeing as RockAuto is a reseller, it is possible they have inadvertently resold me counterfeit parts.

There is a lot of info online about counterfeit DENSO plugs.

Things that appear authentic:
I have tried scratching the ink off the ceramic, it's baked on correctly
I have tried scratching the metal, it seems to be a quality alloy and not cheaply plated
The electrical tip appears genuine according to the various DENSO spot a fake guides
The box appears authentic, good quality printing, bar code seems ligit etc

Things that appear fake:
They have "ASSEMBLED IN US WITH FOREIGN CONTENT" stamped on them rather than "DENSO +++++++" not great quality stamping
The center ground electrode on some appears to be on a slight angle
The printing on the ceramic is slightly blurry in places and not as crisply printed as I'd expect.

Perhaps DENSO has a USA factory, and perhaps it produces a lower quality appearing product than the Japanese factory. As long as it works as well, I don't care. Given all the hype about the precision of the gap and special metals used to improve performance and longevity, the angled electrodes seem to be sloppy manufacturing and negate some of the alleged benefits of the precise tips used.

Compared to Bosch plugs I've bought in the past, these appear very cheap. I was under the impression DENSO was a high quality product and if these are genuine, I'm surprised DENSO would lower their standards.

 

[Gannet167]

More pics

 

[97prizm]

Is there a production or date code anywhere?

 

[ctechbob]

Those look like every other Denso I've used and gone over 100k on. Don't see anything there that would raise any concern.

 

[el Nuke]

why did you go to Rock Auto to purchase them?

If price has anything to do with it, you are seeing the unintended consequences of a race to the bottom in parts manufacturing.

They're the real deal, such as it is.

Use them with confidence; return them to RockAuto if they don't last the full promised mileage.

 

[wagsrk08]

I recently purchased 4 Denso spark plugs Part No. 3421 (SK20HR11) from NAPA only because I wanted to eliminate the fear factor of fakes. Paid almost $4 more per plug than Rock. My factory box they came in is a little more fancier than yours shown. Still made in USA with foreign parts. And yes, I like and trust RockAuto for majority of my internet auto needs.

 

[Carmudgeon]

They look legit to me. Google the return address they were shipped from to determine the actual supplier.

RA is not an AD, and offers no warranty on Denso plugs, and only 60 days on NGK plugs, which suggests the same for those as well.

 

[jdw1222]

Pretty sure those are counterfeit.

I had this exact same plug and same issue. Mine lasted about 8-10k miles before the were shot.
First is a pic of the electrode of authentic plug. Notice the blue tint on the metal

Second pic is counterfeit plug next to authentic. notice the authentic plug doesnt Have the extra metal bump on underside of electrode, like yours shows. . I would go to Napa ,Aa or dealer and buy authentic plug and compare

 

[electroken1]

I have a set of IXEH20TT that have been sitting in the garage for a few years. Just like in the OP's photos, the electrode alignment is a bit off on all four of them and the print quality of the logo is similarly crappy. These claim to be Japan made.

I don't need to think about this too much because the car they were intended for is sitting in a junkyard.

 

[Gannet167]

I bought from RA because they're are few options to buy them in my area and I've had good luck with RA before. The main parts store in my area is Canadian Tire. They don't have them in stock, so RA was the choice.

I do like the price at RA. They were about $11.33 Canadian per plug all in. Locally, these rentail for $13.99. Not a huge savings but they came quicker than the alternative. CT only sells them in groups of 4, which is awkward for a part number specific to Toyota 4.0 V6. RA sells in any quantity.

I've ordered a set from CT to compare. I'm not sure if CT is an AD but I have a relatively good level of confidence that CT buys legit parts. which hopefully I can compare. It would cost me $20 in shipping to return these to RA, and I'd have to find another option for getting 6 plugs, vs 8 from CT. It would just be better if they were genuine and I could put my mind at ease. The current DENSO plugs in there are well worn copper core standard plugs but clearly better made.

If these are genuine, I'm not impressed DENSO. I don't need them to be pretty, just work. But buying their premium product with special electrodes makes no sense if they're built so poorly that the electrodes don't even line up. If they are real, they sure have left me with doubts about authenticity and worries they'll damage the engine if they start coming apart.

 

[Gannet167]

Is there a production or date code anywhere?

What would that look like, where should I look? There are some codes on the box but I don't know how to read them. Box says copyright 2014.

 

[Gannet167]

They look legit to me. Google the return address they were shipped from to determine the actual supplier.

Brilliant! Shipping label and invoice say:

Rock Auto LLC
2782 Eagandale Blvd
Eagan MN 55121

A google maps search of that address reveals Factory Motor Parts.

DENSO'S website says they are an authorized dealer.

Thank you!

 

[el Nuke]

Pretty sure those are counterfeit.

I had this exact same plug and same issue. Mine lasted about 8-10k miles before the were shot.
First is a pic of the electrode of authentic plug. Notice the blue tint on the metal

Second pic is counterfeit plug next to authentic. notice the authentic plug doesnt Have the extra metal bump on underside of electrode, like yours shows. . I would go to Napa ,Aa or dealer and buy authentic plug and compare

I don’t think those are the Denso TTs

 

[slacktide_bitog]

Many Rock Auto parts ship from warehouses owned by Parts Authority or Auto Value, while some ship directly from the manufacturer. Both Auto Value and Parts Authority are listed as authorized Denso suppliers.

I'm not familiar with Factory Motor Parts, but they seem to be another auto parts wholesaler/distributor like the other two I mentioned. There should be no problem with them.

Rock Auto doesn't own any inventory or warehouses. They are a drop shipper. Like the OP did, you can always google the return address to find out where your parts came from.

Denso does have a spark plug factory in Athens, TN. Many US-made Japanese cars have US-made Densos as OE.

NGK has a spark plug factory in WV. They make V-Powers and OE plugs for American cars.

 

[jdw1222]

I don’t think those are the Denso TTs

yes. They are the TT.

Here is a pic. I still have them sitting in my toolbox

To me, the ops plugs look counterfeit

Tough to tell by pictures, and hopefully I am wrong but they don’t look like denso quality @the electrode.

It always possible someone else pulled a switch with a return and the reseller didn't catch it and resold then to you

Do they have a blueish color at the electrode?

 

[slacktide_bitog]

Factory Motor Parts is listed as an authorized Denso distributor
Go here, click on wholesale and spark plugs, enter the zip code 55121, and Factory Motor Parts does show up

 

[Yah-Tah-Hey]

Factory Motor Parts is listed as an authorized Denso distributor
Go here, click on wholesale and spark plugs, enter the zip code 55121, and Factory Motor Parts does show up

Sparkplugs.com also handles Denso products

 

[nthach]

FWIW, I’ve bought Denso plugs off Amazon and they passed the real/fake check. But I’m still leery and next time I need plugs the local parts houses are my place to go(not OR/AZ).

 

[wagsrk08]

For grins and giggles these are 4 Denso Part No. 3421 (SK20HR11) that I just changed in my 2012 Tacoma that I purchased new in 11/2011 now with 98,382 miles on them for a comparison. The only difference between these used OEM and the new NAPA plugs were: the OEM were stamped Japan. The newer plugs were stamped USA. The new box said made in USA with foreign contents.

 

[Elroy the Brave]

Had a similar problem with Denso Iridium plugs. Wore out after 30,000 miles. I also didn't notice any improvement the entire time I used them.

After that I switched to Autolite Double Platinum. Vehicle runs great. I think the Autolite Double Platinum plugs will last a lot longer.