hayllone

Hello guys, thats my first post but sadly, its because a problem with my Civic, so, the car is 95 Civic hatch, engine: d15z1
Its with that 5 wire o2 sensor... So, i have an error code 41 showing, which means: Oxygen sensor heater - circuit malfunction
I'm using Autodata software, and did the suggested testing of the sensor resistance between the pins and it is ok.
Then i proceeded to a test of the voltage which comes to the o2 sensor, and in autodata its written that it should be equal to the batery voltage (around 12-13 V), but sadly i have there around 3-5V ...
Any ideas what can be the reason to do not have enough voltage, and where to search the problem... Thanks!

roy ilkenhans

the connector if not you will have to trace it back to the pcm/ecm

Former User

There are 2 voltage tests, one using the Blk wire as ground and the other using the engine/chassis as ground. What were the voltage readings for each test?

hayllone

Both were equal, exactly 6.8 V , while i got 12.33 on the batery.
I checked the wires, and i found the main one, which is comming from the inside of the car, that is the wire on which we do this voltage test, i did the test again (before any connector) when using the engine as a base, and again 6.8V, this fact makes me sad... the problem maybe is even before the wire start... i dont have idea.. :/ (btw today my o2 sensor was tested on another d15z1 and it is working)

Tomorrow i will post a pictures of the whole path of the wire

Former User

If you follow the service manual instructions, it clearly tells you that the Blk ground wire is bad.

eghatch9295

iTrader: (1)

zing

hayllone

Ok, i followed the manual and - result is Open in the BLK cabel...
But all the wires are so hard to be reached and check where is that problem with the BLK cabel.
So, what this black should be, a ground? And if so, can I just connect that black to a ground, thanks!

P.S : I see that g101 is located at termostath body, and when i connect the YWL/BLK to that, i can see that there is again ~7V , so i dont see a reason that the BLK to be opened..

jlk16188

I had the same issue with my VX. I cut off the ground wire just after the connector in the harness close to the O2 sensor and ran a new ground to the thermostat housing ground location instead of messing with the factory harness in that tight location. Its been working flawlessly for 30K miles now.

hayllone

Ok, i'm heading to the car now and will give a try to that solution, I will let you know if that works (i hope! ) Thanks.

hayllone

Result: Fail.
What i did is, I did a new ground connection, from the harness to the termostat body (the new connection is very near to the sensor.
And again, when i check the V while engine is in idle, between YWL/BLk and BLK , it shows ~7 , ~7.3 V....

Former User

The ECU MUST control ground at the black wire. Otherwise code 41 will be thrown.

hayllone

Ok Ron, I will re-connect the original cables, but any usefull idea how to trace down easier :?

And also, does g101 = termostat body.
Because in the guide is written to check connection between the sensor and that g101, and if g101 is the termostat, to where that black cable is connected before it goes to the LAF, to be controled from the ECU, thanks!

Former User

Edit - My last post was in error. The black wire does indeed ground on the thermostat housing (G101). Run a new wire from the FAF connector directly to G101.

hayllone

Thats what i did, and then, while engine is in idle, I've tested the YWL/BLK and BLK wires, and again 7V, i did this test while the LAF is disconnected

Former User

Provide details and pictures.

Former User

What was voltage to body ground?

hayllone

Again 7V , going down to take pictures

Edit. Here are the images:

Former User

The wire splicing and G101 connection jobs are less than optimal and you also need to consider that the open may be at the pin inside the LAF connector, which your splice does not bypass.

hayllone

what this means: "The wire splicing and G101 connection jobs are less than optimal" what i need to change

Edit: Also, the open cant be in a connector, because i do tested and YWL/BLK to the new orange, and again 7V

tony_2018

I think he meant the brown rectangle connector near the ecu?

hayllone

So far what are the results from the tests:
YWL/BLK - Body Ground - 7V
YWL/BLK - BLK (from the harness) - 7V
YWL/BLK - Orange (my new wire) - 7V (no matter where i test: on the connector or directly on the cable)

hayllone

Any thoughts? I dont know what to check anymore.. :/

hayllone

Still did not found any solution
Any other ideas, what to check :/ Thanks!

hayllone

I'm currently wondering if it can be some relay which is causing that problem..

hayllone