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2016 Optima GT Kia Optima GT
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Discussion Starter #1
So after searching and asking, I couldn't find a solution for running a wire into the cabin through the firewall on a 4th Gen.

So I tinkered myself and decided to write up a DIY.

- The entire housing is made of three pieces. The outer shell, a metal reinforcement plate and the rubber grommet underneath.
- Photos may be reversed for LEFT HAND DRIVE


- 10mm socket (with extender)
- flat head screwdirver
- side cutters
- needle nose pliers


1. Open the the engine bay and locate the large grommet with the main wiring harness. It is located on the passenger side.
2. Using the 10mm socket, remove the two 10mm nuts on either side.
Firewall 1 (Medium).jpg

3. Using the side cutters, cut the cable tie at the bottom holding the plastic shell to the wiring harness.

4. This is probably the trickiest part, separating the plastic shell from the metal plate. There are two ways of attempting this.

a. Using the needle nose pliers, press and push the clip out.
Firewall 2 (Medium).jpg
b. Pry the flat head screwdriver between the plastic shell and the clip of the metal plate.

5. Once the top clip has been dislodged, rotate the plastic shell and metal plate so the bottom clip is now accessible.

6. Repeat step 4.

7. The plastic housing should now be free, revealing the rubber grommet underneath which come off the firewall with relative ease.


In terms of running the wire, up to you whether you want to pierce a hole through the rubber grommet, or strip some of the black tape and run the wire through the grommet.

***Remember to run any wires THROUGH the metal plate and not around it!***
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