When to change plugs on Prius?

Answer 1

I believe the book calls for 100,000 miles. However I experienced a cylinder 3 spark plug mis-fire at about 96,000 and again about 1,000 miles later so I replaced all 4 at about 97,500. Although they looked great, that is a lot of miles and the longest lasting spark plugs I have ever seen. A mis-fire will bring on the feared RED TRIANGLE and disconcerting temporary loss of power (I don't remember the code but code erase was the cure for me). The originals are Iridium not Platinum. The Iridium's are a little more money but worth it in my opinion, be sure to use a little dab of anti-sieze 'cause that is really a long time for spark plugs to stay in the hole.

Mine is a '93 @ about 115,000 miles with rolling average on the screen of 44.4. About 42 in winter and 46 to 48 in summer, to get 48 and up miles per gallon I must drive at 45mph or slower. If you get 38 to 40mpg then you are driving too fast.

One set of plugs, 2 sets of wipers, on my 3rd set of tires. It's had maybe a dozen or so P3191 engine stall after cold start or cold air restart. I finally got my own scanner and just reset after P3191... Throttle Body cleaned recently by dealer on recall and no problem since... NO brake issues - at 104,000 miles I cleaned and rotated my brake pads (now that's a first) the only other maintenance issues were the 12 volt battery died, replaced it with lawn tractor battery - $40... (made new cover w/vent from silicone baking pan) - Toy' wanted about 300 dollars for small 12 volt, not for me. Now have about 1 year on tractor battery from H.D. with no problems, and the drivers door lock has worn out linkage pivots in the door so I must lock by hand - all else is good. Amazing car, love it. Oh, yeah. It's Paid for.