What do these codes mean?

I just ran some codes on my 95 Cobra. It came back with 172,173,176,543. I checked the book and it says that the 172-176 codes are "Heated Exhaust Gas Oxygen sensor- voltage signal indicates "rich", Bank 1 and 2. I just ordered new O2 sensors so that should take care of that problem. They are the original sensors. The 543 code reads this, "Fuel Pump circuit open connection- Electronic Control Assembly to battery. I have no clue what this means or how to fix it! Does anyone know what this means? I would appreciate it if someone can give me some info! Thank you!

Does anyone have a clue on what these mean or a way that I can fix the problem? I really need some advice! Thanks

I have the stock headers on. The only upgrades I have done are K&N, O/R H-Pipe, Flowmasters, pulleyes.