I want to read the codes myself. Where do I do that? I am to jumper what two wires? What blinks the code-- the check engine light itself? Thanks.

Never mind-- reading the "Similar Threads" to the right, here, I found an answer for a Civic that helped. Bright blue socket with a two-pin and a three-pin connector plugged in (the socket just a holder: no other wiring) behind the glove box/under the dash, center passenger side.

It gave me a code 43, "fuel supply system". The forums are saying, among other things, O2 sensor (is that the default for *any* check engine light?) but I'm thinking that with 190K and 15 years it may need a new fuel filter, replaced only once IIRC.

You are right. It could be a problem with the heated oxygen sensor or circuit, but it could also be a fuel system problem; e.g. fuel filter, main relay, fuel pump, or fuel pressure regulator.