99civic08

Hi, longtime reader, first time posting. 1999 honda civic lx d16y7 auto 202k that runs perfect but has a bunch of CEL's that I need help with where to start.
14 IAC (EACV) - idle air control valve
65 Secondary oxygen sensor heater wire (black wires)
67 Cat Converter
71 random misfire cylinder 1
72 random misfire cylinder 2
73 random misfire cylinder 3
74 random misfire cylinder 4

Now I am unsure of where to start. The car has NO idle issues at time. Car has no misfire issues...nothing. She starts perfect, drives perfect, idles fine, etc.
I commute 70 miles (35-35) a day to work and never had an issue whatsoever.

I have a spare 02 sensor that I can swap in, however thats the least of my worries at this time. Ive been reading that cleaning the IAC *sometimes* will take away the code 14, however....most have idle issues - I do not.
From my reading the random misfires I should start with a compression test, however....car is running fine.
Additional information- NGK Plugs (Gapped to spec) NGK wires, cap, rotor all new within 8k miles. (No issues after change during the summer) Of note fuel filter probably has 30-40k on it, Ill grab one and change this weekend

Thoughts, help, ideas?
Thanks!

crazyhorse2011

I guarantee all those codes are related to the same problem, except maybe code 14. I would test the IACV. Unplug the iacv with engine running. does the idle drop and possibly stall? If so we know it's at least open. Then i would remove the iacv and clean it thoroughly with brake cleaner.

I assume you unplugged the battery to clear the old codes out of the computer and these codes are fresh? If not, unplug the battery for a minute, drive around for 50 or so miles and then report back with the newly checked ECU codes.

mk378

Clear the codes, then drive until the CEL comes on again and check right away to see which one came back first. They could be old. Some may never come back.