put in a Bosch 02 sensor, new plugs,wires, 3 weeks ago then the check engine light comes on when I go over 55 miles an hour on the freeway, I was told need new fuel pump
what cause a obd 1 error code 43 in a 91 accord ex on 1991 Honda Accord
Sounds like EGR valve. Its not cheap but easy to replace. Take it out and clean it. Thats worth a try and free !