Guys, I made a discovery when changing spark plugs in my wife's 2013 CX-5. It seems that the factory plugs are by.....wait for it.....Yes you guessed it.... DENSO. The iridium version of this plug is identical to the "factory plug" for much less....... oem plugs are 3-4 times more expensive..... I paid $6.67 ×4 at Rockauto,Com
Enjoy!

 

75k miles already?

 

well, i hope they work. for years, ngk listed iridium plugs for the millenia 2.3. and, for years, owners would buy the iridium plugs, install them, then find out they werent correct, after coils failed, and a whole new set of the correct plugs had to be bought. ngk is one of the oe suppliers to mazda for this car. they SHOULD have the correct info, right? so, when places like rock auto list plugs for cars, they dont know what fits what. they go by the plug(or any other part manufacturer) catalog published by that vendor. if the vendor has the wrong info, like the case of the millenia, then the wrong plug gets sold. i called ngk several times and spoke directly to their tech dept, and each time, they admitted the wrong info was in their system. it took years to get it corrected. i also worked part time for oreilly auto parts, and yup, the store electronic catalog also had the wrong(from the factory) info. of course, i also called oreilly tech, and spoke to them. at first, they put the blame on ngk, because that is where they got their info from. and they even admitted i was correct. it took months to correct the catalog. several other plug manufacturers also listed the wrong info. and here is another tidbit. it applies only to ngk, but i am sure other plug manufacturers have a similar system. the proper ngk plug for the millenia 2.3 is 3741, which used to be PZFR5F. however, most aftermarket stores would carry PZFR5F-11, because it would fit a lot more cars. everything is the same, EXCEPT the gap. -11 means the gap is 1.1mm, WAY to large for the 2.3. the correct gap is .7-.8mm. ngk uses the -11 designation on a lot of their plugs. and the aftermarket counterpeople dont know this important difference. again, lotsa dead coils. some of the aftermarket places would tell the owner to regap the plug. again, ALL plug manufacturers specifically warn against regapping any precious metal tip plugs. again, ngk also had the -11 plug on their website as for the 2.3, and yup, when i would call and tell them it was wrong, they would instantly agree. but it took years for them to make the correction. a few months ago, i used the amazon catalog to buy a set of plugs for our 2013 mazda3, 2.0 base. i input all the correct information, and ordered the plugs. i was a bit suspicious because the price was so low. after installing the plugs, i went for a test drive. within ONE MILE, i got a serious miss, and flashing cel. i immediately returned home, and reinstalled the old plugs, taking note of what they were. with the old plugs, the car ran perfectly. checking amazon, they did carry this plug. i called amazon and complained, and they refunded the total for the order, and sent me the correct plugs. and the wrong info is still on their site. so, i hope you get the correct plugs. just remember, cheaper dont always mean correct

 

She is a real estate agent. Shall I say more? By the way, the plugs work great for me. Hope you have similar results.

 

You might find this thread interesting:High Mileage CX-5s - report in

 

Not knowing the specs of a USA CX5 I'm not 100% certain this will apply. ( I work in the New Zealand & Australian market )

The factory ignition system has a "Ion" sensor setup. Its basically a pre O2 sensor check of combustion using the ignition coil & sparkplug. I can't remember the exact details but I remember being taught we must use genuine sparkplugs and not aftermarket plugs.

Another of my 2 cents to consider before replacing sparkplugs in any Skyactiv Mazda.