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When Should I Change The Spark Plugs In My Toyota Prius?

Toyota Prius does have spark plugs and yes they do need to be changed. The question is when? I will answer that and how you can tell in this article.

Spark plugs are often talked about but not discussed much. We all know that they need to be changed, but when and how often are questions that bring up a lot of confusion to Toyota Prius owners.

In this article, I want to cover when you should change your spark plugs and how you can tell if they need replacing.

Toyota Prius Spark Plug Change Interval
Toyota Prius comes equipped with Iridium spark plugs. The benefits include a high melting point which translates into better performance and complete combustion. Those are all reasons that Prius (and many other vehicles) use Iridium spark plugs, but there is also one better reason, life span.

The average lifespan of an iridium spark plug is 100,000 miles. NGK states that their Laser Iridium plugs last between 80 to 100k miles. In any case, you should be thinking about changing your plugs around the "major service interval" that Toyota suggests is 90k.

How Do You Know If Your Spark Plugs Need Changing?
This question I get asked all the time from Prius owners. If you are not sure whether your spark plugs are original or not, here is a helpful hint.

Original equipment or OE plugs have a white dot on the very tip of the plug. If this dot is present, chances are those plugs are original. Depending on the mileage of the car, they may need to be changed.

Spark plugs, unlike engine oil, can sit for much longer and still be good to go. If you live in an area of extreme humidity and the car has been sitting for quite some time, better to take a look in the spark plug tubes to see if you can see any rust build-up.

Other notable mentions here are leaking spark plugs and soot-coated spark plugs. If a spark plug is leaking, it is time for it to be changed. A leaking spark plug will look like the picture below, where the ceramic portion looks like it has rust on it. This is blow-by, and those plugs need to be replaced.

Toyota Prius leaking spark plug

Soot-covered plugs often result from over-fueling or improper combustion; it can even mean oil burning in the combustion chamber.

Soot-covered plugs need to be a part of a deeper diagnosis as to why your Prius is not operating as efficiently as it can. The chart below (thank you, internet) is a great chart to show you how your spark plugs should look and what is causing some issues.

NGK Spark plug diagnostic chartConclusion
Toyota Prius equipped with Denso iridium spark plugs needs to have them changed about 90,000 miles. Can you change them sooner? Yes. Can you change them later, also yes but not recommended.

I know some person out there has 200k on their OE plugs or something like that who will challenge what I am telling you here today. To that, I would say you are probably doing a ton of highway driving and light load conditions. In that case, your iridium plugs can last much longer.

Now that you know look out for the YouTube video I will have on changing spark plugs for Toyota Prius. That is all for today, and remember, Today's Adventure is Tomorrow's Story.

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Peter Neilson is an automotive consultant specializing in electric cars and hybrid battery technologies. He holds a Bachelor of Science in Automotive Service Technology from Weber State University. Peter can be reached on Linkedin and you can tweet him at The_hybrid_guy on Twitter. Find his page on Facebook at Certified Auto Consulting. Read more of Peter's stories at Toyota news coverage on Torque News. Search Toyota Prius Torque News for more in depth Prius coverage from our reporter.