Big Turbo Wideband Sensor Issue

[Mythbuster74]

So I have a 2000 a4 1.8t that I swapped the ECU for a 018ch out of a 2001 awm car. Wired it the first time kinda half ass, had a off and on o2 sensor code (heater circuit I believe). After that I redid it and got another o2 from the junkyard, this time soldered nicely with heat shrink. Didn't fix the issue.

Went back the junkyard got the wiring from the sensor connector alllllll the way to where the pins go into the ECU. This time I installed the pin connectors just like they do at the factory, put it back together, same issue. I'm kinda doubting it's my wiring at this point, as it's nicely put together and same issue.

The car runs very rich at idle, does this have something to do with the issue? It runs rich at idle because the mass air needs more tuning and when the computer sets the o2 sensor code it stops using the o2 sensor, so you get no correction.

I'm about to buy a new o2 sensor, if that doesn't work a new engine harness, and if that doesn't work another ECU.

Anyone have any ideas? Anything not hardware wise that could cause this issue?

[Seerlah]

Heating element is only for warm up so you don't burn the sensor out. It has nothing to do with the sensor's function for fueling. What maf sensor are you using? When converting you need to use all sensors associated with that ecm from cam window, cam sensor, to injectors, to oxygen sensor.

[Mythbuster74]

Heating element is only for warm up so you don't burn the sensor out. It has nothing to do with the sensor's function for fueling. What maf sensor are you using? When converting you need to use all sensors associated with that ecm from cam window, cam sensor, to injectors, to oxygen sensor.

Well now after the most recent rewire it's throwing just the regular o2 sensor circuit. The ECU is only a year not even newer, so from what I've seen you only need the extra wideband wires, but I also have installed the matching maf because I know they're slightly different. Also has 80lb dekas, with the correct injector data in the ECU.

I'm going to go the junkyard later this week to find another engine harness to rule out the loose connection issue which that code would appear to indicate. Audi's are kinda rare there, but they have a abundance of passats. Do you guys think a Passat harness would work correctly? From another awm? I've heard the awm has different knock sensors but those should be easy to change.

[Seerlah]

Not sure about the harness. But I have a manual AWM and retrofitted an auto harness. Those go cheaper on ebay than manual harnesses. I made a diy on how to go about it, if you choose to opt this route.

[Mad Cow]

Passat harness should fit with no or minimal modifying. I had weird issues when I ran an atw harness with AWM electronics, ended up buying and modifying an AWM harness. Some connectors are different but you can pull the pins out and transfer them to the old style connector bodies. Or get the new sensors, there's maybe 5 or 6 max that are different.

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