kapoosh valve

arrgh.. so i have a d16z6 in my 91 civic si. running a p28, ob1 dizzy, 4 wire o2 sensor.

the sensor is brand new, and the wiring is correct to my knowledge.

car throws code 41 with or without the o2 sensor plugged in. it runs very rich. (18-22mpg)

i tried another ECU pulled from a running car and it does the same thing.

can anyone shed some light on this for me?

EE_Chris

There are 3 parts to the system: The O2 heater element, the wiring, and the ECU.

The O2 heater element should measure 15-40 ohms. The wiring should not be open or shorted and should have continuity from the O2 sensor plug back to the ECU plug. If the O2 heater is good and the wiring is good (and you've got +12v to one wire with key-on), then next up is the ECU.

If the O2 sensor is new and another ECU from a car that doesn't throw this code are installed and you still get the code, then you know what to check.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kapoosh valve &raquo;</TD></TR><TR><TD CLASS="quote">...and the wiring is correct to my knowledge.</TD></TR></TABLE>

You need a Helms and you need a meter to check how correct it is.\

Where are you at in MD?

kapoosh valve

the wire that is grounded when the key is off and then gives a pos. 12v when key is on is the heater wire, correct?

i have a chilton manual and a multimeter.

i am located in northern harford county md. probably about 45mins to an hour from ellicott city. if you are confident that you can help me out, i'll pay you to come up here and fix it. or buy you dinner. or give you some parts. or something.

my jumper harness is one of the first ones that JKOBD made. its kinda primitive but i got it from H-T member 'dash' and he says it works. its kinda ghetto but the wires for vtec and the o2 sensor are marked and i have the instructions it came with.

EE_Chris

Since you have a meter, try this:

Unplug the O2 sensor from the main engine harness and measure the resistance between the two black wires - does it come out to be 15-40 ohms?

If yes, with it still unplugged, do one of the black wires have +12v on it when the key is on? Don't use the 'ground' for the heater element - just use the engine.

If yes, with it still unplugged, is the other black wire shorted to ground at all?

If no, does that black wire have continuity back to A6 (heater control for a P28)?

If yes, try another ECU.

Basically, you just made sure that the heater element isn't burned out, that it is receiving battery voltage with key-on (no need to check for shorts to ground on this wire - if it were, a fuse would have blown), and that the heater control wire has continuity back to the ECU in order for it to control the heater element.

kapoosh valve

pardon my ignorance, but i dont have much experience with ohms...

how do i measure the resistance between the two black wires?

EE_Chris

Notta problem. In the picture, you'll notice a green scale - see its symbol?



Since the O2 heater is only 15-40 ohms, for this particular meter, you would put it on the 200 range. Does your meter have a similar scale?

MugenHonda

I am having a similar problem, I keep throwing a code 41, where does the green wire go?
It says to ground it, I grounded it but I am still throwing a code.
any ideas?
thanks its pissing me off because the other 3 wires, one black is wired to a25, white is wired to d14, and the other is wired to a6.
The only wire i ran to a ground is the green.
thanks, for some reason, my car also has 2 map sensors, one from a obd2 is this suppose to be?
thanks

EE_Chris

You have things wired wrong.

One black goes to A6 the other black has to go to a switched +12v. There is a connector that feeds all the injectors with power - use this same source - its the factory location.

The green wire is the actual O2 sensor ground and goes to D22. The white wire is the O2 sensor signal and goes to D14.

As for having two MAP sensors - no, OBD2 does not, nor does OBD1. However, before Honda started mounting the MAP sensor on the throttle body, they had it mounted to the firewall.

You should buy a Helms.

kapoosh valve

i think i only have one place on my meter for ohms. i'll have to check when i go back to the garage.

MugenHonda

i looked at d22 and it was a green and white wire.
I mounted it and melted my ground for the vtec solenoid

MugenHonda

I am running a p28

MugenHonda

i was quoted to just ground the green wire anywhere on the motor
I tried connecting it to the green/white wire on the map sensor, which is the same as d22 and shorted my ground for the vtec solenoid

EE_Chris

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MugenHonda &raquo;</TD></TR><TR><TD CLASS="quote">i looked at d22 and it was a green and white wire.
I mounted it and melted my ground for the vtec solenoid</TD></TR></TABLE>

It should be a grn/wht wire - so good to go there.

What do you mean by 'mounted' it? I'm not sure how connecting the green wire from the O2 sensor to the grn/wht ground wire of the MAP sensor would cause the VTEC solenoid to melt, as you're correct - the grn/wht wire does go to D22.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">You have things wired wrong.

One black goes to A6 the other black has to go to a switched +12v. There is a connector that feeds all the injectors with power - use this same source - its the factory location.</TD></TR></TABLE>

My fualt - you do not have thing wires incorrectly for the O2 heater. A25 is a switched ignition source - so things look good there.

Even though you don't have the green wire hooked up - this would not cause the O2 heater code to be thrown.

Bust out a meter and measure the O2 heater resistance to see if its in spec.

kapoosh valve

so i measured the resistance between the two black wires on my o2 sensor and it came out to 17ohms.. so that checked out.

my friend and i checked the other things you mentioned and everything checks out.

we know the ECU, o2 sensor and the connections are good. the only thing we're thinking could be a problem with the jumper harness itself somewhere...

do you have any other ideas? on another forum someone said that it could be something in the distributor wiring..

OnePointFive

while i was going to school in dekalb, IL (small town in the middle of nowhere) my hatch was constantly throwing this same code. i figured i burnt out the o2 sensor cause i'd street race a bit and figured maybe that was the cause. school was over in a few weeks so i waited till i went home to replace the o2, well i get home, the night i come back my gas is on "E" and i filled it up with gas here back in Aurora, after it running for 5 minutes with the new gas it went away and it hasn't been back since.

mine's no d-series, but that's another possibility.

cliff notes: bad gas perhaps?

EE_Chris

Don't know how the distributor wiring could come into play here. The two 'systems' aren't even related to one another.

Why would you think it to be the jumper harness? If you measured continuity from the one black wire back to A6 and it showed 0 ohms - thats the only interaction the ECU has with the O2 sensor, as far as the heater section is concerned.

And you said you measured +12v with the key-on, so that + 17 ohm O2 heater section + wire to A6 is not shorted to ground and has continuity + good ECU (how sure are you) = ???

mrsmartness

Here's what we got:

Ignition Off: 3 -12v & 1 Nothing
Ignition On: 2 -12v, 1 +12v, 1 Nothing

These were taken at the o2 sensor, therefore the wiring is correct?

The nothing wire should be the o2 signal, and the switched +12v should be the white heater wire, right?

You can mix & match the blacks (-12v) if I am not mistaken?

This would mean our wiring is correct and the ECU was tested in another ex and found to be fine.

This brings me back to believe that even though we got a 17 ohm resistence between the 2 black wires on the o2 sensor, the o2 sensor may be bad?

Some help guys, we are confused. Thanks

kapoosh valve

tony (mrsmartness) summed it up. we're working on this together.

as we were looking at the wiring diagrams we noticed that a few of the wires associated with the o2 sensor go directly to the main relay. could there be any problems associated with that? to my knowledge, the main relay is functioning properly as far as fuel pump control and all that.. although the motor is running extremely rich...

any help would be awesome. we've been messing with this for quite some time now.

EE_Chris

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrsmartness &raquo;</TD></TR><TR><TD CLASS="quote">Ignition Off: 3 -12v & 1 Nothing
Ignition On: 2 -12v, 1 +12v, 1 Nothing</TD></TR></TABLE>

I'm not sure what this notation means.

The two black wires are the wires you need to be concerned with. One of those black wires is a switched +12v source - so if it came from the main relay, that sounds correct (and logical). The fact that the O2 heater measures 17 ohms is fine - its in good working order as far as I can tell. The green wire is the O2 sensor signal and the white is the O2 sensor ground. Neither of these two wires has anything to do with the O2 heater section unless somehow something inside the O2 sensor shorted out. Is there continuity from any of the black wires to either the green or white wire (O2 sensor is unplugged at this point)?

Is there continuity from the other black wire back to A6 (through the jumper harness)?

kapoosh valve

-12v = ground. he's saying that with key off, we have 3 grounds and one that reads nothing

with key on, we have 2 grounds, one positive 12v and one nothing.

EE_Chris

I still don't really understand what it is you're talking about.

There are two wires to be concerned with - they are both black.

Unplug the O2 sensor. Is there battery voltage on one of the black wires? If yes, then you're done with this wire - if it was shorted to ground, you'd have a blown fuse and would not measure battery voltage.

Measure continuity from the other black wire back to A6 - is it 0 ohms? Since the ECU connector A should be unplugged and the O2 sensor is still unplugged, does that black wire measure anything to chassis ground - it should NOT.

kapoosh valve

so umm yeah. we fixed it.

thanks for your help, EE... it took a simple comment you made for us to figure out our stupid mistake.

mrsmartness

yeah, dumb mistake thanks again

EE_Chris

Well speak up - for all you guys know, it could very well be someone elses problem too.

....unless there was never really a problem to begin with....is that what you're hinting at

Glad to see you got things fixed though.