I am replacing front and rear motor mounts on my 2000 infiniti i30.

The sensor harness from the rear mount runs all the way from the mount in the rear of the engine bay to the front.
When I replace it with the new mount, I don't see a way to run the harness from the mount to the connector near the air intake. Way too crowded, no room to get my hand or even a tool. I can't keep track of the harness with a flash light.

What happens if I leave the sensor disconnected?

 

In my experience, disconnecting both the front and back increases engine vibration at idle somewhat. The extra vibration doesn't annoy me. I disconnected both because I do not want either engine mount to short out and fry a component and brick the ECU. I don't know how much vibration you'll have with the front mount connected and rear mount disconnected. I suggest disconnecting both. The only issue that will arise is a little extra engine vibration depending on how much the front mount is worn.

 

Most of us have disconnected our engine mounts long time ago (to avoid problems caused by them shortening).
On my car (2000 Maxima SE) I could not detect any increase in vibration, be it idle or in gear.

 

I'll keep them disconnected.

Do any of you have a pic of the motor mount orientation?
The rear one was off by about half inch when I tried to put it back.

 

Turn it around Lol