I keep getting this code 43 on my ecu I have been dealing with it for like 2 months now here is a list of things that I have changed for it already:
Denso O2 sensor (Brand New)
Fuel pressure Regulator (tried 3 of them)
Swapped ECU`s (Have a spare)
Main Relay (Have a spare)
Fuel Filter (Brand New)
RC Injectors (Brand New)
Fuel Pump (1 year old)

The only thing that I notice is when i start the car the fuel pressure with vacuum will be at 50psi and after running the car for a while (like 20 mins) it will drop down to 40-45 psi with vacuum at idle. I didnt see any fuel leaks under the hood could the hose in the tank be leaking? What should I do next?

 

Oh yeah this does not happen every day when i drive it may not do it for a couple days and then it may do it everytime i drive somewhere. What could make it so random?

 

Yeah, your fuel pressure is too high. Check for possible leaks in the vacuum line to the FPR. Another possibility is a clogged fuel return line.

You also may have a problem in one of the two wires that runs between the O2 sensor and ECU.

When the code 43 is thrown, does the engine run fine or are there running problems?

 

I used to have this code before. My problem was an exposed wire by the fuel pump. During sudden turns the wire would lightly ground out and cause the code to appear, check you wiring.

 

Yeah I would definitely check your wiring on this one. More than likely this is being thrown by the wiring to your O2 sensor, but as a previous poster it could be fuel pump or another related fuel components (injector wiring, main relay wiring etc)

Chilton and Hayes manuals are OK for the average do-it-yourself type person, but where they always fall short is with the electrical troubleshooting. Do yourself a favor and get a Honda Factory Service Manual, much better choice in my opinion. You can pick them up from a dealer sometimes, or some people selling them on here. OR you could goto http://pdftown.com/PDF-Honda-Civic-1...ce-Manual.html and just download it.