Newbie Maintenance Help/Advice - 2015 Prius V Wagon

get the plugs from a dealer, an online one is okay for best price. there are too many chinese counterfeits running around the supply chain.
you don't need to change the wires if they look okay. and they should on a 2015.
it might be smart to use a torque wrench if you're not familiar with tightening plugs.
how many years/miles have you owned her?

 

The hardest part of changing the plugs is gaining access to them. To do so the windshield wipers, motor and steel mounting assembly has to be removed.

I like the detail in this video

Mervs egr and Wiper Cowl Video

Disregard the intake and egr part which is more complicated and not needed to change the plugs.

 

If your car has LED lower headlamps and headlamp washers (among other features) it is a Five. Many early Five cars show up as Threes, though I haven’t seen that on a 2013+ model year.

 

Video #13 linked here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

is very helpful. One thing though, he applies anti-seize liberally to the new spark plugs, and mentions torquing them to 20 ft/lbs. repair manual says 15, and makes no mention of lube, I’d stick with that.

the BIG hurdle with gen 3 Prius (and Prius v) is the engineering oversight, that the coils atop the spark plugs cannot be removed, without first removing the wipers, windshield bottom trim, wiper linkage/motor, and the underlying metal cowl.

A 3/8” drive torque wrench is appropriate for 15 ft/lb.

you’ll need a 6” extension to reach down the spark plug tube, and the spark plug socket size is 14 mm (9/16” also works).

A typical “spark plug socket” has a rubber insert designed to grip the plug. If they’re excessively grippy you can end up leaving the socket on the plug, pulling off the extension. Accordingly, it’s good to tape the extension/socket junction.

Toyota has revised the original spec’d Denso SC20HR11 to SC16HR11, a slightly “hotter” plug. There are lots of reports of counterfeit plugs; I would buy either the Toyota branded ones from dealership parts department (they’re the Denso, just repackaged), or get the Denso, from a reputable local automotive specialty store. Avoid Amazon and eBay.

one caution, since it happens so frequently: there’s a torque spec in repair manual for the small hold-down bolts for the coils (black gizmos that push onto the spar plugs). The torque spec is in INCH pound, which are twelvefold less than foot pounds. There are several reports here, novice DIY’rs miss that, snap the heads off. Bottom line: use common sense when installing fasteners. In this application, I wouldn’t use a torque wrench for anything other than the spark plugs, just snug everything firmly.

attached is some info from repair manual. Not all that helpful, and the myriad parts removal not mentioned, off somewhere else in the manual. The last page I needed to paste in, was also somewhere else in the manual, had the spark plug torque spec.

 

The early gen 3 Prius liftback trims had Roman numerals: I, II, III, IV, V.

Then the Prius v wagon (lowercase v) was introduced, and to try even harder to avoid confusion, the liftback trims were changed from I, II, III, IV, V to One, Two, Three, Four, Five.

Looks like some Autozone data entry routine matched up the Prius v wagon with the Prius liftback V.