I am in the middle of a headgasket project.
I smudged the marking tags on the O2 sensor wires and can't identify my markings.
Is there a simple way to define which connectors go to which?
The connectors look alike. They seem to be in pairs.
Anyone have any insight?
I could hope to find an X5 in the junkyard to examine but I don't think there are any at the moment.
Anyone have a photo?

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2001 x5 3.0 (sold with broken motor), 1990 e30 M3, 1991 318is, 2002 325i, 2008 335i Dinan stage 3 6 speed,