Spark plug replacement - miles or years?

I have a 2006 Prius (bought new) with 256K, and I've never replaced the plugs. Car passes California smog tests by a large margin multiple times. My car may be an anomaly, but I worry more about keeping the oil changed than the plugs. Either they work or they don't. Still getting around 43-44 mpg. Personally, I think if you start messing with the plugs, you invite problems.

 

I don't see why. Still that's pretty amazing. I would replace them; they've had a good run, lol.

 

Yep, those are the sort of stats that say "don't mess with success."

Keep watching the MPG; that's the spark plug's canary in the coal mine.

 

The other canary of lower mileage is an indicator that one or more hybrid modules is starting to fail (less voltage capacity means more gas engine usage).

 

Agreed but there are steps for differential diagnosis once that arises. Also when the plugs are really poor you'll start gathering misfires, P030x codes.

 

Healthy Plugs won’t play much of a factor when it comes to emissions.

 

Hello, I am new to fixing hybrid vehicles. Would you please help me?
I have to replace compressor on "2011 Toyota Prius 4 Cylinders N 1.8L MFI HEV DOHC", my only concern is not get electricuted
After I remove SERVICE PLUG GRIP and disconnect negative 12v battery cable, do I need to worry about anything else?
Thank you very much.
Jeet

 

You can always test before touch to ensure there is no flowing electrons.

But if you disconnect the orange safety plug, that will be a good start.

Good luck and keep us posted.