https://www.mangago.me/read-manga/telework_yotabanashi/
the ml is a systems engineer
dunno ones where both of em are PRECISELY doing engineering, but semantic error’s a close recommendation
you and i can’t do this
https://www.mangago.me/read-manga/we_re_still_in_the_spring_of_life/
https://www.mangago.me/read-manga/boku_tachi_wa_mada_aoku_daigaku_nyuugaku_hen/
not engineering, but they're in STEM here https://www.mangago.me/read-manga/perfect_fit/
these might be more longshots, but maybe you'll like them
https://www.mangago.me/read-manga/the_honest_life_of_a_game_studio/
https://www.mangago.me/read-manga/regression_in_3_seconds/
any bl or straight romance where one or both of the main characters r engineering majors?… usually I find that most college life bls have them majoring in english, korean, business, marketing, etc and not so much STEM lol. The closest one i know is one room TA (which is peak btw) and they were biology majors