The recommended interval to change the spark plugs on a Prius is 120,000 miles.
Here’s a DIY guide on how to change the spark plugs from your 3rd gen, 2010-2015 Toyota Prius. Be sure to read the entire guide completely before attempting.
With the windshield wipers, cowl, motor assembly and sub-assembly removed, we now have full clearance needed to access the spark plugs.
P.S. Enjoy your Prius for another 120,000 miles! I’ll write up a DIY guide on replacing the spark plugs from a Prius c once my wife’s car reach that point.
<p>My 2012 Prius Four has reached 120,000 miles and symptoms of rough idle, cold start rattle, decreasing fuel efficiency and sporadic loss in power (especially during acceleration), has become almost a once-a-week routine. I figured it is time to replace the spark plugs. I am having major service as recommended by Toyota done to the Prius sometime this month and figured I’d shell out an extra $50~$100 to have them replace the spark plugs at the same time, so I called my dealer and requested a quote. My jaw basically dropped. I was quoted $290 and as a courtesy, the service lady offered $50 off, still $240. I called another dealer that I’ve been going to since 2012 and was quoted even higher at $368!! There is no way I am paying ~$300 to have $40 worth of parts changed so I decided to change it myself. After changing the spark plugs, fuel efficiency increased and displaced power from the Prius has returned. Stepping on the gas doesn’t feel like the Prius is struggling and no more cold engine rattle from the ICE during warm up cycle. For this project, I used NGK (4912) ILKAR7B11 Laser Iridium Spark Plugs. They are pre-gapped to Prius spec (1.0-1.1 mm). Depending on where and when you buy them, they cost between $9.00 ~ $11.00 each. You’ll need four. The entire spark plug replacement process costs about $45 in parts (4 spark plugs, 1 packet of anti-seize grease) and a bottle of ice cold beer. The entire procedure took me exactly an hour and 30 minutes while taking photos. I suspect it would take probably about an hour without all the photographing.</p>
<h2>Tools and Materials Needed</h2>
<ul>
<li><a href="https://amzn.to/2Wq0ggL" rel="noopener noreferrer" target="_blank">9/16 magnetic spark plug socket</a></li>
<li>14 mm socket</li>
<li>10 mm socket</li>
<li>Flathead screwdriver</li>
<li>Ratchet</li>
<li>Needle nose pliers</li>
<li><a href="https://amzn.to/2WrOvGq" rel="noopener noreferrer" target="_blank">Anti-seize grease</a> (optional)</li>
<li><a href="https://amzn.to/2WlswRD" rel="noopener noreferrer" target="_blank">4x NGK (4912) ILKAR7B11 (4912) Laser Iridium Spark Plugs</a>. These are pre-gapped.</li>
</ul>