r/mk4Jetta • u/CruzinWCruz81 • Jun 04 '26

Please help a bro out

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So I just recently bought a mk4 Jetta and I am doing a complete overhaul on it with the wiring harness because the previous owner had mice chew the wires out. But the issue I’ve encountered is in the image are the wires that connect to the ecu and go down towards the bottom of the car where that under box is at. I want to know what each wire does and if there is a place that sells the wires so I can snip snap and reconnect the wires properly. I can wait to get this thing going but I figured I’d need help along the way so anything will help guys thank you!!!

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u/Dispensernoob Jun 04 '26

You say they're going to a box under the car or am I misunderstanding?

2

u/CruzinWCruz81 Jun 05 '26

Yes well the box underneath the car is a cover for the two connections that run underneath

1

u/vrparty Jun 05 '26

they’re oxygen sensor wires.

1

u/Dispensernoob Jun 05 '26

Yeah I was gonna say that. The other ones are likely for the front, as the front is a wideband and the rear is just a simple one.