symptoms of dead sparkplugs

Googling the signs of a bad spark plug, can help much more.

Its a general feature when plugs are/or go bad.

 

What kind of problem are you having? How many miles on your plugs and on the car.

 

I had one skipping 30mpg was an indication, is your emergency brake dragging?

 

The Gen2 spark plugs are iridium tipped, whereas iridium is one of the most valuable elements on Earth because it is so hard and does not break down. So you could conceivably go life of vehicle, but they get hard to remove after the recommended 125000 mile limit. Many of us go longer. But if they pooped up, then you could get some missing sparks I guess. I did mine once at 135000 miles, and that's it for me. Gen2 is nice because Gen3 they made it harder to DIY plugs.

If it's a used Gen2, you never know what somebody else put in there for replacement plugs unless you pulled one for inspection, you should be able to see the iridium holding the gap.

 

Being in service near to the mileage that Toyota says to change them.

Engine running rough and/or setting mis-fire codes.

Spark plugs usually don't go "dead" suddenly; they usually get marginal first.

 

Our 2007 had 230k on it when I got around to changing the plugs. I was not noticing anything unusual about the ICE performance, I just thought that 230k was a lot of miles for a set of plugs. (I had no evidence the previous owner had ever changed them.) Anyway, none of the plugs that I took out showed anything unusual that might affect performance. It was probably a waste of money to have changed them, but it did make me feel better.

 

A symptom would be a code for misfire on an advanced scanner.

Takes about 10-15 minutes to change them. Not hard or expensive.