Found this for you on the web. Good luck.
What is code 43?
Code 43 is "fuel supply system."
This code will trip when the ECU and the readings from the o2 sensor
don't get along(in layman's term or easy enough for Si Speed to
) read the above two threads).
How to diagnose and fix?
First things first, when was the last time you changed your O2 sensor?
Start by replacing that first because most likely, that's the main
culprit. Now, you may wonder why doesn't the CEL indicate code
41(heated o2 sensor)? Usually when the o2 sensor is completely dead,
that code will trip. Also, even though the o2 sensor is working, the
voltage or ground isn't 100% Because of that, it will correlate with
If replacing the o2 sensor did not help code 43 to disappear, next thing is to replace your fuel filter. A clogged fuel filter will also trip code 43.
Next up, did you install an aftermarket Fuel Pressure Regulator?
I have a few friends with 3rd gen Preludes and both of them installed
aftermarket FPR's and they too, trip code 43. Him and a lot of people
who install aftermarket FPR's mess with the PSI and that will cause code
43 to appear(on a stock ECU mind you). Bring it back to stock PSI to
help fight code 43.
Those are the 3 main culprits that will cause code 43 from my
experiences. Injectors, spark plugs & wires, most likely anything
"fuel' related that isn't working properly will also cause code 43.