I have a 1988 Audi 90 4cyl I can not find the O2 wiring I have 4 wires near the battery box. Big Green one with 2 wires a Brown Hot wire and a Blue not conected. Are these the ones that go to the O2 sensor. From the O2 I have 1 black two whites. Can someone with a 90 help please?

THe 02 sensor wires go from the sensor, over the transmission and plug in near the middle/bottom of the engine on the driver's side. It's quite a long pigtail!

follow/trace the wires back up to the engine bay! ;O)

And in the case of the 4cyl - it's difficult to trace from down underneith - took me a few minutes to notice in snaked over the top of the tranny and over to the other side.

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always had the O2 wires located in a different place! No 2 Audi's, that I've seen, were the same. Because of previous replacements, place the wires where ever.

Thats why I wrote for him to locate his O2, and know for sure he's got the correct wires! ;OP

Its not about "time" but having the correct wires ;O)

The connection for the 02 on the four cylinder is right next to the distribur cap, and is fixed to the bell housing of the tranny with a small clip that holds it in place. From there it snakes over the top of the tranny and down to the 02. There's no other way to run the wiring being that it has to go to that connection which is held in place by the wiring on that side of the engine. So, yes, all 4cyls that I have seen ARE the same, which is why I was giving the guy easy info on how to find it based on my own experience. There is a slight possibility that someone else on this forum might know something too, you know? :-)