o2 sensor wiring.

[Twest7740]

I've been fighting this problem for awhile now, And have came to the conclusion that my o2 sensor wiring harness is bad because of the splicing the the previous owner did (origanly had an a4 swapped to a1) so the extended the harness to the downpipe. I was wondering if i could just rewire the o2 sensor instead of getting a complete engine wiring harness? Thanks in advance.

[GhostAccord]

What are your current wire colour and connector pin combinations?

[Twest7740]

What are your current wire colour and connector pin combinations?

The four colors that run to the connector are, yellow/black, orange/black, white, and green white. They go through the connector and connect in this order y/b goes to black, o/b goes to black, White goes to white, And g/w goes to green.

[GhostAccord]

Only two that might be be mixed up would be the two black wires. They are for the heater circuit. Are all of the splices soldered properly and making good connection, no resistance?

What is the problem that has lead you to the O2 wiring?

[Twest7740]

Only two that might be be mixed up would be the two black wires. They are for the heater circuit. Are all of the splices soldered properly and making good connection, no resistance?

What is the problem that has lead you to the O2 wiring?

Everyone on here says a spliced harness will not allow the right resistance and you will have to replace the harness, the wires are not soldered but they are connected well by wire connectors. On one of the black wires I was testing it was only getting 8 ohms when it was supposed to get 12. Wires that run from ecu to the connector are good though. I'm not sure hy that one wire wasn't getting 12.

[jewelproject]

didnt the a1's have 2 o2 sensors? if it was swapped from an a4 to a1? what was the big difference, beside the obvious? i dont get why they would have to rewire the o2 wiring? is it because the connector was female and not male? my ex has a male o2 connector....sorry if im sounding dumb. im just trying to understand this topic for my own benifit, i guess.

[GhostAccord]

A spliced harness, if done properly with good quality solder, should not effect resistance and can work just as good as a complete harness. That being said, I have also seen electrical tape pigtail connections work without issues as well. Not that I would suggest doing that though.....lol

As for only getting 8ohms instead of 12. That sounds like the sensor might be the culprit there. A bad connection would usually give you more resistance not less.

didnt the a1's have 2 o2 sensors? if it was swapped from an a4 to a1? what was the big difference, beside the obvious? i dont get why they would have to rewire the o2 wiring? is it because the connector was female and not male? my ex has a male o2 connector....sorry if im sounding dumb. im just trying to understand this topic for my own benifit, i guess.

The difference is the placement of the O2 sensor in the exhaust manifold. The two have them in different locations on the exhaust. Therefore, if you wanted to run a different header you would need to ether relocate the O2 bung or extend the O2 wires. Usually cheaper and easier to extend the wires.

[deevergote]

Many spliced connections work fine. I always advise against it, because the quality of a splice will clearly vary from person to person depending on ability, and the option to simply maintain the stock harness and use correct parts, or build a subharness, is always there. Unless, of course, in a situation like this, where the previous owner spliced (or in my case, the shop that did my swap...)

If the wires are mixed up, you should always get a code 41 for the o2 heater circuit.

I say undo the previous owner's splices and re-do them yourself. Follow these instructions here and you'll get the best possible results.

[Bad_dude]

If you suspect the harness, test its resistance?

[Twest7740]

Many spliced connections work fine. I always advise against it, because the quality of a splice will clearly vary from person to person depending on ability, and the option to simply maintain the stock harness and use correct parts, or build a subharness, is always there. Unless, of course, in a situation like this, where the previous owner spliced (or in my case, the shop that did my swap...)

If the wires are mixed up, you should always get a code 41 for the o2 heater circuit.

I say undo the previous owner's splices and re-do them yourself. Follow these instructions here and you'll get the best possible results.

I've already rewire it. The previous owner had used electrical tape. I'll try to reverse this two Black wires and see what happens. But were it is spliced one of the black wires is getting 8 volts(said ohms earlier) and the manual says it should have 12.

[Twest7740]

I have already replaced the sensor with an ntk sensor. I'm getting a code 41 for the heater. But I meant volts when I said ohm before. Where the splicing is dot it's getting 8 volts instead of twelve. Before splicing and we couldn't figure out why it is doing that?

A spliced harness, if done properly with good quality solder, should not effect resistance and can work just as good as a complete harness. That being said, I have also seen electrical tape pigtail connections work without issues as well. Not that I would suggest doing that though.....lol

As for only getting 8ohms instead of 12. That sounds like the sensor might be the culprit there. A bad connection would usually give you more resistance not less.



The difference is the placement of the O2 sensor in the exhaust manifold. The two have them in different locations on the exhaust. Therefore, if you wanted to run a different header you would need to ether relocate the O2 bung or extend the O2 wires. Usually cheaper and easier to extend the wires.

[Twest7740]

Alright so on the connector i switched those two black wires around at the splicing and it did the same exact thing. I reset the ecu and about a minute after the car being on the check engine light came on, Still a code 41.

[youngflyndsaved]

I have already replaced the sensor with an ntk sensor. I'm getting a code 41 for the heater. But I meant volts when I said ohm before. Where the splicing is dot it's getting 8 volts instead of twelve. Before splicing and we couldn't figure out why it is doing that?

I hope you can figure out the problem, i'm having the same one with code 41. I bought a brand new NTK sensor, reset the ecu and still got 41. This past week i replaced 2 wires from the engine harness, i soldered a yel/blk to a 12v source and ran an orange wire straight to the ecu. I reset the ecu and still getting 41. The next thing i'm contemplating on doing is changing out the 2 white wires on the engine harness as well. But i'm still not sure if those white wires are HO2S/heated oxygen sensor circuit related.

[Twest7740]

I hope you can figure out the problem, i'm having the same one with code 41. I bought a brand new NTK sensor, reset the ecu and still got 41. This past week i replaced 2 wires from the engine harness, i soldered a yel/blk to a 12v source and ran an orange wire straight to the ecu. I reset the ecu and still getting 41. The next thing i'm contemplating on doing is changing out the 2 white wires on the engine harness as well. But i'm still not sure if those white wires are HO2S/heated oxygen sensor circuit related.

I know ive had this issue for awhile, A code 41 is just the heater not the actuall o2 sensor. Its got me stumped.

[Twest7740]

Okay so the orange/black wire is the wire that is getting 4 volts now. it is supposed to be grounded to the ecu how can this be fixed?