ecu code 16 & 41, help!!

whats up? this is my first post in the intgra section. i have an 89 civic dx with a complete 94 gsr swap. complete meaning motor,tranny,ecu. the guys over at Locash Racing made me a custom engine harness with a matching ecu adapter. there for my car is now obd1. anyways....when i did the swap, the cat didnt reach the midpipe. so i drove around like that for a day. then i made a pipe that fit and hooked up the exhaust(tanabe catback) and ever since then i get two codes from the ecu. code 16 says fuel injector system defective or unplugged..? how if it worked fine beforehaust was hooked up...and code 41 says primary oxygen sensor-heater. is that just the o2 sensor should i really worry?? SORRY FOR THE LONG STORY!! ANY HELP OR SUGGESTIONS WOULD BE APPRECIATED!! THANX!!