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2016-2020 Kia Optima Trunk Side Trim Panel: Damage, Fitment, and Replacement Guide

This guide covers the essential details for identifying and replacing the left or right trunk side trim panel in your 2016-2020 Kia Optima, including part numbers and hybrid model considerations.

4 minutes to read 2016-2020 Kia Optima
Difficulty
2/5
Est. Time
0.5 hrs
DIY Doable?
✅ Yes
Shop Labor
$50 - $100
Used OEM Price
$50 - $120
Safe to drive — A damaged or missing trunk side trim panel is a cosmetic issue and does not affect the safety or mechanical operation of the vehicle.
Key Takeaways
  • This is a trunk side trim panel, NOT a passenger seat cover.
  • Verify the correct side (Left/Driver or Right/Passenger) before purchasing.
  • Fitment for Hybrid and Plug-In Hybrid models may be different; match the part to your specific Optima model.
  • When buying used, the most important inspection is checking the back for intact mounting clips and tabs.
The trunk side trim panel, officially called the 'Trim Partition Side' by Kia, is the carpeted or molded panel that lines the left and right sides of the luggage compartment. Its primary function is cosmetic, providing a finished look to the trunk and covering the vehicle's metal body structure, wiring, and the back of the wheel well. It also offers a small degree of sound deadening from road noise. These panels are typically made from a molded, fabric-covered composite material designed to withstand light impacts from cargo.

Symptoms of a Damaged Trunk Side Trim Panel

Failure of this part is purely cosmetic or structural and will not affect the vehicle's drivability. Damage is almost always caused by loading or unloading cargo, or from items shifting during transit.

  • Visible Cracks or Gouges: The most common issue is physical damage from sharp or heavy objects hitting the panel.
  • Stains or Discoloration: Spills from liquids can permanently stain the carpeted surface.
  • Loose Fitment or Rattling: The plastic clips or mounting points holding the panel to the car's body can break. This will cause the panel to become loose, move around, and potentially rattle against the metal frame, especially while driving.
  • Warping or Deforming: Extreme heat or moisture from spills can cause the panel's backing board to warp, ruining its shape and fit.

Known Issues, TSBs, and Recalls

There are no Technical Service Bulletins (TSBs) or recalls issued specifically for the trunk side trim panels on the 2016-2020 Kia Optima. Issues with this part are related to wear and tear or physical damage rather than a manufacturing defect.

Related Recall Notice: While not involving the trim panel itself, a significant recall (NHTSA Campaign Number 23V594) was issued for 2016-2018 Optima models, including Hybrid and Plug-in Hybrid variants. The trunk latch base could crack, preventing the trunk from being opened from the inside with the emergency release. This poses a safety risk. 🎬 Watch this news report on the trunk latch recall. Before working in your trunk, it is critical to verify with a Kia dealer or on the NHTSA website that this recall has been performed on your vehicle.

🎬 See how to replace the trunk latch yourself.

Buying a Used Trunk Side Trim Panel

A used OEM panel is an excellent, cost-effective alternative to a new part. Since this is a cosmetic item, a visual inspection is key.

What to Check Before You Buy:

  • Verify the Side: This is the most common mistake. Ensure you are buying the correct side for your needs—Left (Driver Side) or Right (Passenger Side). Part numbers are side-specific.
  • Inspect All Mounting Points: Carefully examine the back of the panel. Look for broken or stressed plastic clips, tabs, and mounting holes. These are essential for a secure, rattle-free installation. A panel with broken tabs will never fit correctly.
  • Check for Physical Damage: Look for deep gouges, cracks, or holes on the front-facing surface. Minor scuffs are normal for a used trunk part, but significant damage cannot be repaired.
  • Look for Stains and Warping: Check for any dark spots, water marks, or discoloration from spills. Lay the panel on a flat surface to ensure it is not warped or bent out of shape.
  • Confirm Hybrid vs. Non-Hybrid: The trunk configuration of the Optima Hybrid and Plug-In Hybrid models may differ due to the placement of the high-voltage battery. This can affect the shape and size of the side trim panels. Always confirm the donor vehicle was the same type as yours (standard, hybrid, or plug-in hybrid).

Cost of 2016-2020 Kia Optima Trunk Side Trim Panel

Part Type Estimated Cost
New OEM $170 - $260
New Aftermarket Not commonly available
Used OEM $50 - $120
Shop Labor to Install $50 - $100

Replacement Information

Replacing the trunk side trim panel is a straightforward DIY task that requires basic tools. The main challenge is carefully prying the panel off without breaking the plastic clips.

  • Difficulty: 2/5
  • Estimated Time: 0.5 hours
  • Tools Needed: Plastic trim removal tool set, socket set (for any cargo hooks or tie-downs).

Pro Tip: Always use plastic trim removal tools instead of a screwdriver. Metal tools will easily scratch or gouge the plastic trim and surrounding painted surfaces.

Technical Specifications and Part Numbers

These part numbers are for the main side trim panels. Always verify the exact part number with a dealer using your vehicle's VIN before ordering.

Side Part Name Part Number(s)
Left (Driver) Trim Partition Side LH / Trim Assembly Luggage Side 85784-D5000WK, 85730-D5000WK
Right (Passenger) Trim Partition Side RH 85785-D5000WK, 85785-D5000

Frequently Asked Questions (FAQ)

Is this the same as a seat cover?

No. Despite some confusing internal naming, this is a hard, carpeted trim panel for the side of the trunk (luggage compartment). It is not a fabric cover for any of the passenger seats.

Will this part fit an Optima Hybrid or Plug-In Hybrid?

Maybe not. The Hybrid and Plug-In Hybrid models have a large battery pack that reduces trunk space and can change the shape of the trunk interior. This may require different side trim panels. It is critical to source this part from a vehicle that matches your exact powertrain (gas, hybrid, or plug-in hybrid).

Can I fix a cracked or broken panel?

Generally, no. The panels are made of a molded composite material that is difficult to repair effectively once cracked. Attempts to glue or patch the panel will likely be visible and may not hold. Replacement is the best option.

Do I need to disconnect the car battery to replace this panel?

No. This trim panel does not typically have any electrical components attached to it, so there is no need to disconnect the battery for replacement.

Avoid Costly Repairs: DIY Guide to Trunk Latch Replacement for KIA Optima/Hyundai Sonata
Avoid Costly Repairs: DIY Guide to Trunk Latch Replacement for KIA Optima/Hyundai Sonata
Kia Optima How To Change Trunk Cargo Area Light Bulb 2016 2017 2018 2019 & 2020 With Part Number
Kia Optima How To Change Trunk Cargo Area Light Bulb 2016 2017 2018 2019 & 2020 With Part Number
2016 KIA Optima Trunk Latch Repair
2016 KIA Optima Trunk Latch Repair
Kia cars could trap people in trunks, 320k vehicles recalled
Kia cars could trap people in trunks, 320k vehicles recalled
Kia recalling around 320,000 cars due to trunk latch issues
Kia recalling around 320,000 cars due to trunk latch issues

Technical Specifications

OEM Part Numbers: 85784-D5000WK 85730-D5000WK 85785-D5000WK 85785D5000

Molded composite with carpeted finish. Attaches with plastic clips.

Wrenchy
Article researched & written by
Go-Parts' AI research assistant. Every article is backed by live web research, verified OEM data, and real technician knowledge — so you get accurate, up-to-date information you can trust.
Meet Wrenchy → Updated Jul 21, 2026

The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.

Year Coverage
This article covers the Seat Trim Panel for:
  • Kia Optima: 20162017201820192020
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