schtima

I have a 94 Civic VX that has had a CEL for a while.

I recently checked the code and it's a 41. I have a manual and it said to troubleshoot by testing a variety of things, including voltage between the black and the yellow-black wires in the hookup. I tested these (with the sensor disconnected) and get only 6 volts.

I have seen the posts about the short issue (http://www.tegger.com/hondafaq...e.pdf), but none of my fuses are blown (which I'm pretty sure would include fuse 15, but they're not numbered, so I don't know what the 15 refers to).

So I think I don't have the short. What I'm wondering is if I can just give the O2 sensor a new 12V feed or if some other action is suggested/required.

It seems to me that the O2 sensor is ok, or at least not the primary problem, because I see the 6V with it unplugged. (Unless the ECU is only sending it 6V because it "remembers" that it's got issues...) I'm hoping it's not the ECU, because I'm guessing that's a major expense and effort to repair!

Thanks for any info.

1fastsi

Woah wait...IIRC Honda O2's don't run on 12v they have a 5V reference voltage.
...and seeing that you run a VX you have the 5 wire O2 sensor.
Cel 41 is in the O2's heater circuit.
I can check the factory 94 VX manual at work tomorrow,and get you a better idea of what to do.
I will also look at the 94 ETM for a look at the wiring schematics...


Modified by 1fastsi at 12:33 AM 11/11/2008

schtima

Hmmmm.... that's interesting.

I do have a vx and it does have the 5 wire sensor. I did see that CEL 41 was the heater - in my manual it specifically says heater voltage, which was why I thought the 6V might be the issue.

The manual I have said that I should see battery voltage between those wires. But the manual is not specific to the vx, so perhaps that's incorrect...

I'll be curious to hear more.

Thanks for responding.

honda.lioness

From http://media.honda.co.uk/car/o...8.pdf for a D15Z3 engine, see if your yellow-black terminal is the same as the orange-black terminal. If so, the manual says look for an open in the black wire between the oxygen sensor and a connection on the thermostat housing.

Failing this, seriously consider just buying a new oxygen sensor, especially if (1) this is a non-OEM sensor; or (2) it is older than around five years. Oxygen sensors do degrade in performance over time, and they will not always throw a code when the degradation occurs. Denso or NTK should be the OEM manufacturer. See http://www.autopartswarehouse.....html for a good deal on your Civic's sensor. Also, Amazon has some OEM sensors for your car that are also a good deal.

schtima

Thanks for the response.

Looking at the diagram, your orange-black is my yellow-black (or perhaps I just mis-remembered).

I will look for the open black. Could you give me any guidance on finding G101?

I was resigned to buying a new O2 sensor, but when I found the voltage issue, I realized that I didn't want to spend that money if there's a bigger underlying issue.

Appreciate the help!

Relic1

keep in mind that with the VX, the ECU supplies the voltage to the heater (unlike every other honda)
6V means that the ECU has either tapered off control the heater (running half power) or something is wrong with the wiring or ECU.
test the O2 heater, should read 10-100ohms. anything more or less than that and it needs to be replaced.

G101 = thermostat housing

lastly, unless you have a 93-95 cali-spec VX, and not the more common 49-state VX.
that link to the autopartswarehouse.com O2 is incorrect. the VX uses a NGK L1H1 wideband O2. (stay clear of the walker versions also)
this would be the one you'd need... http://www.autopartswarehouse.....html
all though it can be had for 100-150.


Modified by Relic1 at 12:54 PM 11/11/2008

TomO

LAF Troubleshooting
G101 location
LAF Heater Troubleshooting
^^^Those are from the factory Helms and should help you accurately diagnose the problem. These are specific to your VX.

honda.lioness

Even the http://www.densoproducts.com site sends one to the 234-4209 sensor for the 94 VX, and only the 234-4209, though it notes California. I see reviews of it at the autopartswarehouse site, and neither reviewer is from California, though of course it is possible they bought California manny'd Hondas.

Curiously, the Denso California version //seems// also to be listed at http://www.autopartswarehouse....Civic.

California standards are higher, so I wonder whether there is really a problem here.

At any rate, I would want more clarification before ordering a new one.

Relic1

92 cali, 92-95 49-state spec VX's use the L1H1.
93-95 cali use a standard 4-wire.

many sites are wrong with the VX, it's sort of the black sheep of the civic.
Best way to be sure, check what you have and go from there. There is the occasional cali-spec VX that pops up.
ECU code will tell you... 37820-P07-Xxx
A = 49-state
L = cali

BUT, the 92 cali had the L1H1... so if you have the L00, you still need the more expensive O2.

honda.lioness

At the densoproducts.com site, and consistent with what you wrote, denso says the 234-4209 sensor is 4-wire, so no joy for the OP, who wrote he has a 5-wire sensor.

Thanks for correcting my mistake, Relic1.