My 98 honda civic just failed the California smog inspection for NO emissions at 15 mph, everything else was fine. I took it to a shop approved by CA for doing smog repair.

The shop states engine computer has not set a code , but the smoke test and pressure test and scope test have identified a slow oxygen sensor and a weak catalytic convertor. If these things are wrong, should there be a computer code?

The quote is $1300 for 'non after market parts'- but no mention of exactly which parts. I did ask for an itemization. Does this seem reasonable?

What can I do that's affordable, and are there codes?