HI, ive done a search for code 43 and i have found a bit of info on what could be causing it, but no one seems to have a the same symptoms as i do... i have a hesitation in lower rpm range. 1k-4500. i do need to change my fuel filter, and i can check my O2 and plugs. all my grounds are good too. i have a jdm b16a its obd1 and i have a 96 hatch. its rewired to OBD1. but back to the CEL and hesitation? any suggestions? Ive heard that TPS can cause hesitation? it could be this cause my lagging is consistant... thank you ahead of time

joe

 

43 - Fuel supply system

check your fuel filter, fuel pump, injectors.. everything that has to do with your fuel

 

lot of times that code has something to do with o2 sensor. from my experience.

 

Usually a code 43 will have to do with the O2 sensor even though it says fuel supply system. My guess is a bad O2 heater.

 

If the O2 heater were bad, the ECU would let you know quickly (Code 41).

If you've got over 75-80k miles on your stock O2, don't expect too much more out of it.

 

From my experiences code 43 is cleared 90% of the time by replacing the primary oxygen sensor.

If a sensor is slow enough to cause a mixture problem it doesn't always throw a CEL for the sensor itself oddly enough.

When you follow the diagnostic flow chart for this code 43 the end result is a oxygen sensor, but i'll double check the chart to see what other possibilities there are.

 

Okay so the diagnostic flow chart says this:

When the car exhibits a drivability problem along with a code 43, then you must check the fuel supply system - i'll get to that in a minute.

If the car doesn't echibit a drivability problem then the only possibilities are the oxygen sensor itself or the wiring and pins for it OR a bad ECU - nothing else.

So about that fuel supply system...could it be any more vague? Here's what it could be:

Fuel pump
Main relay
Fuel lines
Injectors
Fuel pressure regulator
Fuel filter

Of those items the easiest to change are the filter, the pump (call 1-800-962-8922 for IAS and ask for a low mileage used Integra GS-R pump - ask for Randy or Larry Jr. and tell them Tom sent you), main relay, and the regulator.

I'm not usually one for just throwing money/parts at a problem, but unfortunately in this case even the honda book/all Data gives little solutions.

 

thanks for the responses...

my fuel pump is brand new, lines are good, main relay works well, a friend and i traded... how does a filter throw a code with out a sensor? my injectors are from my single cam. i could check my fuel regulator...so you think since i have poor drivabilty its not O2? thanks

 

This is going in circles....test/replace your Primary O2 sensor they are known to cause rough running with / without CELS.

 

I suppose a fuel filter could contribute to a CEL if it caises a problem with the flow of fuel. True there is no sensor on the filter itself, but if it has a blockage then it can cause the CEL indirectly.

The same thing happenes when you have a bad valve adjustment on an OBD2 car. It'll throw codes for "to rich" or "too lean" if the valve lash is too far out of specs even though the valves have no sensors on them.

 

I would try changing the fuel filter first. That's just me though...