Coil resistance test (ohms)

I haven't seen a spec mentioned for PRIUS coil packs.

The interwebs say anywhere from a half ohm to as high as 2-ohms for coil packs in general.

I use a fairly good meter (Fluke 289) and when I touch the test leads together the value fluctuates between 0.08 and 0.09-ohms.
If your meter goes to zero and remains there with the test leads shorted, then your meter might just be rounding down values below an ohm or two...
(Fluke says a new set of test leads will typically be in the 0.1 to 0.3 ohm range)

So.
You said coil packs
In my experience, these usually don't fail at the same time....and for a 2012 it would be sort of unusual for them all to be not-coiling at the same time due to age.
Coil packs are aptly named.
There's not much to them.
They're typically either going to be blown open, shorted, or there will be a non-zero resistance value.
Easy way to tell if somebody isn't toting their load is to take a poll.
Measure all 4 coil packs and see if there's an outlier.

If you're chasing a code, then you could swap the coils around, and see if the symptoms change.
We see this a lot in the forum when the dreaded "Cylinder Miss-fire" (change owner) codes arise.
If you ARE chasing a cylinder missfire, then you may want to (DO want to!!!) rule out a head gasket failure.

If you've changed the spark plugs recently, and you bought the replacements on-line make sure you didn't get knock-offs - especially if you got them from eBay, Amazon, etc...

Good Luck!

 

Some info in this. Plug resistance is spec'd and measured, but the coil test seems to be just good vs bad?

 

I guess you might be able to measure the secondary resistance, if that's what you want.

You'll never measure the primary coil resistance, because there's a whole transistorized igniter circuit inside there. You'd have to saw the thing open to get to the primary coil connection. From the accessible terminals, you can only try to "measure the resistance" of an electronic circuit.

 

Even when one fails, the failures may not be so strongly correlated as to justify replacing all four. Some things just last a long long time and fail somewhat randomly, and it makes sense to replace one if it happens to fail, and deposit the price of the other three into the unplanned-maintenance fund, where it might end up getting used for something else next, instead.