Where Is My Second Upstream O2 Sensor?

S

snoopaloopy

Member
So I attempted to replace my upstream O2 sensors from my 2004 E85 3.0i M54 today to see if that would solve my persistent lean codes.

I took off the cover and one sensor is very easy to locate. First connector and it’s right under. However, the second connector to it seems to be connected to a much longer wire, I traced it down and seems to be another sensor into the exhaust and I can see another one next to it, those must be downstream sensors then.

So where is my second upstream sensor??

Can’t seem to find any specific tutorial or YouTube for this one.

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Also are upstream o2 sensors supposed to be the same length? This one connector is next to the first upstream sensor connector but looks like both ends are much longer.

I thought pre cat bank 1 and 2 sensors are the same short lengths, at least that’s what they look like on rockauto

EDIT: I have located the second port. It’s right underneath but tracking this long wire is such a hassle. Does it come like this from factory or mine was replaced?
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Finally able to locate the second one. It’s so hidden under and behind the manifold.

The wiring of this second sensor is long and goes around only to comes back under. It’s different from all the replacement parts I’ve seen with short wiring.

Is this how they come from factory?
 
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