Hey, all.

I have an 02 WRX wagon, manual. 68,000 km.

A couple of days ago, the CEL came on - solid, then blinking, then
solid. And the car was sluggish, moreso at low rpms.

I called the dealer, and had it towed, even though it was technically
driveable - the flashing CEL had me spooked.

They pulled codes 301 and 303, which (according to workshop manuals I
downloaded in PDF) mean misfire in cylinders 1 and 3.

They swapped coil 1 for 2, and 3 for 4 (I say that like I know what it
means - and I really don't). The CEL went away, but the dealer said it
could come back - the swap was partly to narrow down the problem - if
I get CEL codes 302 and 304 now, they'll replace the hardware. The
issue is not, according to them, engine-threatening, and they didn't
recommend throwing hardware at the problem right away.

Now: I admit I'm an uneducated dork when it comes to auto mechanics. I
want to understand where these coils actually are, what they do, and
why they might go bad. And what does it mean when they go bad? Is it a
'wear' issue? Something electrical? Did they have to pull the heads to
get at these things, or are they part of the ignition system?

I would have asked at the dealership, but everyone was busy and the
gal that rung me in obviously knew nothing beyond what she read on the
work order.

Again, I do have these workshop manuals, but they're more a recipe
book for fixing stuff, where I am looking to understand how it all
works.

Any suggestions of online resources?

Thanks,

BD