CEL Code 43 Fuel Supply System

[Darkshowdo]

Well i posted in a diffrent thread but was off the subject of it so ill start this one.

When Running the car for about 15 mins. the CEL comes on.
with the code 43 and i cant seem to find out why its doing this.

I know is the Fuel Supply System

Ive have reseted my ecu just in case. but still happens

Any help could be appreciated.

[turboAccordHSF]

Well i posted in a diffrent thread but was off the subject of it so ill start this one.

When Running the car for about 15 mins. the CEL comes on.
with the code 43 and i cant seem to find out why its doing this.

I know is the Fuel Supply System

Ive have reseted my ecu just in case. but still happens

Any help could be appreciated.

any change in your cars performance?

[ExplodingCake]

Code 43 is the most hard code to diagnose.

Check your fuel pressure.

[Darkshowdo]

any change in your cars performance?

Doesnt Seem so, I can still push the thing really hard up to about 80mph then ill slow it done. doesnt seem so though.

though maybe gas comsumption it seems pretty bad. seems to be using a lot.


As for my Fuel Pressure, how do i check that?

[mozzandherb]

Code 43 is a hard one to diagnose, but don't overlook your O2 sensor, that might be the problem

[ACCLUDE91]

It is gonna be to high/low fuel pressure (fuel pump or fuel filter or fuel press. regulator or blocked fuel return line), incorrect air/fuel (injector(s) or O2 sensor).

Is this happening on a stock fuel system or do you have any mods done to the fuel system?

[batever]

It is gonna be to high/low fuel pressure (fuel pump or fuel filter or fuel press. regulator or blocked fuel return line), incorrect air/fuel (injector(s) or O2 sensor).

Is this happening on a stock fuel system or do you have any mods done to the fuel system?

since his car is eating gas probably the o2 sensor or something else to do with the fuel/air mixture.

[Darkshowdo]

Stock Fuel System Nothing done with it.

Im thinking the o2 Sensor, and Maybe just replace the fuel filter just incase.

yeh It seems to go threw gas easily. Put about 10 dollars in the other day. Got me to about a half a tank. and now its about a quarter or just above after only like probley 20 miles?

[batever]

Doesnt Seem so, I can still push the thing really hard up to about 80mph then ill slow it done. doesnt seem so though.

though maybe gas comsumption it seems pretty bad. seems to be using a lot.


As for my Fuel Pressure, how do i check that?

You should be able to push it to 115 mph or so without much problem, though I don't recommend it for legal and safety reasons. If you're saying you back off at 80 that's ok, but if the car backs off by itself or tops out there something is wrong.


to check fuel pressure, you get a fire extinguisher and throw away your cigarettes and lighters so they are far far away.

Disconnect the primary wire from the ignition coil so the car won't actually start,.

get a fuel pressure guage and plug it into the fuel rail at the fuel pressure relief bolt.


Now have someone crank the starter engine over while you watch the fuel pressure guage. The car won't start but you'll get a fuel pressure reading off of the fuel rail.

You'll need a new washer to seal the pressure relief nut on the fuel rail when you're done.

Fire extinguisher is just in case but don't do it without one around (on that works for gasoline fires).

It sounds most likely though that it could be an issue with the 02 sensor, which gives the ECU a reading as to how much oxygen is in the exhaust so the ECU can adjust the fuel injector spray. Since you say the car is eating gas.

[Darkshowdo]

You should be able to push it to 115 mph or so without much problem, though I don't recommend it for legal and safety reasons. If you're saying you back off at 80 that's ok, but if the car backs off by itself or tops out there something is wrong.


to check fuel pressure, you get a fire extinguisher and throw away your cigarettes and lighters so they are far far away.

Disconnect the primary wire from the ignition coil so the car won't actually start,.

get a fuel pressure guage and plug it into the fuel rail at the fuel pressure relief bolt.


Now have someone crank the starter engine over while you watch the fuel pressure guage. The car won't start but you'll get a fuel pressure reading off of the fuel rail.

You'll need a new washer to seal the pressure relief nut on the fuel rail when you're done.

Fire extinguisher is just in case but don't do it without one around (on that works for gasoline fires).

It sounds most likely though that it could be an issue with the 02 sensor, which gives the ECU a reading as to how much oxygen is in the exhaust so the ECU can adjust the fuel injector spray. Since you say the car is eating gas.

Well yeh Im just backing off on it cause of safty reasons haha.
It accelerates just fine. i get to 80 in no time. that f22 kicks.

anyways I dont have the tools for the Fuel Pressure. so i think i wont be able to check that.

Ill try replacing the o2 sensor. Should i just get stock Honda one? or Another brand?

but now I have no clue where the o2Sensor is located at.

Im a electrician so i don't have a problem with wiring it.

Just need a location maybe a picture would be easier for me to understand it to.

[batever]

Stock Fuel System Nothing done with it.

Im thinking the o2 Sensor, and Maybe just replace the fuel filter just incase.

yeh It seems to go threw gas easily. Put about 10 dollars in the other day. Got me to about a half a tank. and now its about a quarter or just above after only like probley 20 miles?

Wow that's a lot of fuel for 20 miles.

This problem is a bit outside of my expertise, but I believe how you would go about it diagnosing it would be you hook up an electronic voltmeter in the 0-1000 millivolt range out through the firewall or through a cracked window and under the hoodto the O2 sensor and mount it to your dash you can see a live feed on the 02 sensor output which will tell you if the sensor is off or not (or if you're just testing the 02 sensor at a standstill, of course you don't need to put the voltmeter in the driver's cabin).


There are a number of other tests you can do with an oxygen sensor.
I think I remember that depending on your use of the throttle under load (like accelerating up a hill for example, or holding the engine at x rpms while going up a hill, using the brake to help keep the car at the rpms while you use the throttle to give heavy load to the engine) and whether you are at high rpms or not,, the 02 sensor should give off characteristic readings--which I can't remember now. If it doesn't you need to put another one it--but only use a HOnda one as the aftermarket ones don't work so well with the ECU.

02 sensor readings are only valid (and paid attention to by the ECU) when the 02 sensor reaches about 600 degrees Fahrenheit. It should put out about 200 millivolts I believe when the car is at hot idle. It acts like a battery and puts out varying voltage according the the oxygen present around the sensor.

[Darkshowdo]

Wow that's a lot of fuel for 20 miles.

This problem is a bit outside of my expertise, but I believe how you would go about it diagnosing it would be you hook up an electronic voltmeter in the 0-1000 millivolt range out through the firewall or through a cracked window and under the hoodto the O2 sensor and mount it to your dash you can see a live feed on the 02 sensor output which will tell you if the sensor is off or not (or if you're just testing the 02 sensor at a standstill, of course you don't need to put the voltmeter in the driver's cabin).


There are a number of other tests you can do with an oxygen sensor.
I think I remember that depending on your use of the throttle under load (like accelerating up a hill for example, or holding the engine at x rpms while going up a hill, using the brake to help keep the car at the rpms while you use the throttle to give heavy load to the engine) and whether you are at high rpms or not,, the 02 sensor should give off characteristic readings--which I can't remember now. If it doesn't you need to put another one it--but only use a HOnda one as the aftermarket ones don't work so well with the ECU.

02 sensor readings are only valid (and paid attention to by the ECU) when the 02 sensor reaches about 600 degrees Fahrenheit. It should put out about 200 millivolts I believe when the car is at hot idle. It acts like a battery and puts out varying voltage according the the oxygen present around the sensor.

Well thats a rough estimate but yeh. Its close I mean Its probley in the range of 15mpg so yeh i dont know lol. But ill do some more driving tomorrow and really find out.

But as for testing the o2 sensor. If the car is stand still and i hook up a volt meter to the o2 sensor?

Where is the O2 sensor located at picture would be better if can provide one.

[Skidd]

If the o2 sensor detects how much air/fuel is in the exaust, its mounted to the exaust manifold somewhere. In the CB7 case, its almost under the engine, but if you lift the car, its fairly easy to get at. It'll be the only wires that go to the exaust, and it is located just to the passenger side of the oil filter... I guess its possible to get at it without lifting it, but... Its a pain to get under there normally. and as far as I know, to remove the old o2 sensor, the exaust has to be hot so the metal has expanded enough to release the threads on the sensor. I tried to get mine off when the exaust was cold and I could not do anything with it.

Good luck!

[Darkshowdo]

If the o2 sensor detects how much air/fuel is in the exaust, its mounted to the exaust manifold somewhere. In the CB7 case, its almost under the engine, but if you lift the car, its fairly easy to get at. It'll be the only wires that go to the exaust, and it is located just to the passenger side of the oil filter... I guess its possible to get at it without lifting it, but... Its a pain to get under there normally. and as far as I know, to remove the old o2 sensor, the exaust has to be hot so the metal has expanded enough to release the threads on the sensor. I tried to get mine off when the exaust was cold and I could not do anything with it.

Good luck!

alright ill lift my car and check it out thanks

[batever]

Well yeh Im just backing off on it cause of safty reasons haha.
It accelerates just fine. i get to 80 in no time. that f22 kicks.

anyways I dont have the tools for the Fuel Pressure. so i think i wont be able to check that.

Ill try replacing the o2 sensor. Should i just get stock Honda one? or Another brand?

but now I have no clue where the o2Sensor is located at.

Im a electrician so i don't have a problem with wiring it.

Just need a location maybe a picture would be easier for me to understand it to.

If you want to diagnose it tell me what year and trim level of car (ex, dx, lx) you have and I'll tell you what my Haynes manual tells you to measure. There's not only the sensor, there's also the sensor heater and a simple voltmeter and ohmmeter will give you a heads up as to whether to replace it.


I don't have a pic of it but the o2 sensor is the thing that's sticking out way at the bottom of your exhaust manifold way down by the downpipe if you have a DX though on the EX it's in the exhaust downpipe. and it has wires coming out of it. On my DX you can see it standing in front of the car and looking down at the base of the exhaust manifold.

It's a bear to remove, I'm told. Due to the high exhaust temperatures baking it into the threads.

And yeah, use a Honda one. But really I'd diagnose it a bit before putting a new one in, I think they are somewhat pricey although a call to your local HOnda dealer will let you know.

Of course you could just replace it that's true. My Haynes says you'll need a special socket with slots in it for the electrical connectors to fit through to remove it. You'll need to heat the car up to hot running condition before attempting to remove it as well. then turn the car off and disconnect the negative battery terminal, raise the car up on stands, disconnect the connector from the sensor, unscrew the sensor, and put the new sensor in, tightening securely. (put antisezie compound on the new o2 sensor's threads or you'll really regret it if you have to ever remove it again). REconnect the connectors, and give the car a drive.


For more info, here's some more info from my Haynes manual says:

code 42 (not 43--don't know if this is a misprint or not. the Haynes doesn't have a complete trouble code list)

fuel supply system--check fuel pressure, fuel pressure gregulator and oxygen sensor, as well as for vacuum leaks.

I'd check all of the vacuum hoses too then. ]

The o2 sensro ranges from an output of 0.1 v (high o2, lean mixture) to 0.9 v (low oxygen, rich mixture). The ecu monitors this output to attempt to maintain a 14,7 to 1 ratio of oxygen to fuel in the combustion chamber. (this is to help the catalytic converter out and stop emissions)when there is a prob with the o2 sensor or its circuit the ecu operates in open loop mode, controlling fuel delivery according to a default value instead of feedback from the o2 sensor. (In other words, the car is going to eat gas, because the default will be a conservative value that produces a rich mixture to prevent harmful detonation in the combustion chambers)

The sensor has a pgitail and electrical connector on it which should not be removed. Keep the connectors clean and keep grease etc off of it as well as the louvered end of the sensor.

Don't drop or handle it roughly.

The silicone boot must be installed correctly or it will melt and the sensor won't work right.
That's what the Haynes says. It gives some diagnostic tests with the voltmeter and ohmmeter which I can tell you about later after I've had some sleep if you need the info.