How to verify OEM spark plug compatibility Prius Gen3

DO NOT purchase spark plugs from ebay or amazon. There are just too many counterfeits out there.

get the 3444 plugs from RockAuto.com they're less than $10 each and will be actual denso plugs, not some chinese imitation.

 

I used the twenties in my cars down here in the southeast United States where it's really hot most of the Year always have most all toyz come w 16 HR or did forever . I always used the 20 since working at dealer down here . I use the long life model of whatever plug series I'm using at time denso. Makes a bunch . Fine wire racing etc .

 

Can't remember where I heard it, but the story was the 16's are a slightly hotter plug, ie: they'll burn off deposits better. The owner's manual says 20's, but Toyota revised, presumably due to plugs building up deposits. I had the 20's for 12 years, looked virtually new when I pulled them after 12 years (and 95k kms), replaced with the 16's, per Toyota's recommendation.

I'd just go with the Denso 16's, that's the recommendation.

Sort of the exception, but this time round the dealership parts department was actually cheaper than my usual local automotive go-to place. Are you near a dealership?

 

Good price, but maybe counterfeit?

FWIW, I paid $16.50 CDN apiece for mine, in 2022, through dealership. The Toyota part no (it's the denso, just in different box) was 90919=01275.

 

lol at $4 a plug they're guaranteed to be counterfeit.

 

Choosing a hotter plug improves burning off of deposits, at the trade of a lower safety margin from pre-ignition (the hotter plug tip may ignite the mixture before the spark is timed to occur). That's what makes the choice a trade-off, and not just a simple "get hotter plugs, they'll stay cleaner" rule.

The language and the numbering are tricky. Denso uses lower numbers for hotter-running plugs (so 16s run hotter than 20s). Some other manufacturers use an opposite numbering convention.

Denso uses the term "low heat range" (and a low number) to mean slower heat dissipation toward the plug shell—meaning a plug that stays hotter. They use "high heat range" (and a high number) to mean faster heat dissipation toward the shell, meaning a plug that runs cooler. So in Denso literature, "low heat range" means a hot plug, and "high heat range" means a cold plug.

NGK avoids that mess by not even using terms like "low heat range" or "high heat range"—they say "hot heat range" or "cold heat range" (respectively!), instead.

Heat Range | Basic Knowledge | SPARK PLUG | Denso

Understanding Spark Plug Heat Range - NGK Spark Plugs

 

If plugs are like pics they look purdy good the lettering on the silver . But that's a show pic. And they're 15.99 a pop