Automatic Transmission Assembly for 2016-2020 Kia Optima
Product Notes Read before buying
This transmission is for US-built Kia Optima models with a 2.4L engine and front-wheel drive. Please verify that the first digit of your vehicle's VIN is '5'. For 2016-2018 models, please also verify the 8th digit of your VIN is '3'.
Voice or type your vehicle details and Wrenchy will confirm fitment in seconds.
Vehicle Fitment Guide
This part fits the following vehicles:
| SubmodelSUB- MODEL |
Body Style | Years | Engine | Attributes |
|---|---|---|---|---|
| EX | Sedan | 2016 - 2019 | L4 2.4L | FWD | Automatic |
| Hybrid | Sedan | 2016 | L4 2.4L FULL HYBRID EV-GAS (FHEV) | FWD | Automatic |
| Hybrid EX | Sedan | 2016 | L4 2.4L FULL HYBRID EV-GAS (FHEV) | FWD | Automatic |
| Hybrid EX Premium | Sedan | 2016 | L4 2.4L FULL HYBRID EV-GAS (FHEV) | FWD | Automatic |
| Hybrid LX | Sedan | 2016 | L4 2.4L FULL HYBRID EV-GAS (FHEV) | FWD | Automatic |
| LX | Sedan | 2016 - 2020 | L4 2.4L | FWD | Automatic |
| EX Pack | Sedan | 2017 - 2019 | L4 2.4L | FWD | Automatic |
| EX Tech | Sedan | 2018 | L4 2.4L | FWD | Automatic |
| S | Sedan | 2018 - 2020 | L4 2.4L | FWD | Automatic |
| Special Edition | Sedan | 2020 | L4 2.4L | FWD | Automatic |
Know This Transmission Before You Buy
The research behind our purchase interview — recalls, bulletins and real install economics for this transmission family:
A quick look at your own vehicle makes sure the right transmission shows up:
- Verify VIN 1st digit is 5 (US-built).
- Verify VIN 8th digit is 3 (2.4L Theta II GDI engine).
- Confirm vehicle is Front-Wheel Drive (FWD).
- Confirm original transmission barcode sticker reads OEM part number 45000-3BYE0.
What the install really takes — plan and budget with confidence:
Special tools this job needs:
- Engine support bar/bridge
- Transmission jack or subframe jack
- CV axle popper tool or slide hammer
- 32mm axle nut socket
- Professional bidirectional scan tool (Kia KDS, Autel, or Launch)
Budget for these consumables at install:
- Kia Genuine ATF SP-IV (or SP-4M / SP4M-1)
- Front cover rubber gasket/seal
- Torque-converter seal / Front pump seal (OEM part #46131-3B000)
- Axle seals
- Transmission cooler-line flush solvent
What your vehicle’s computers will need after the swap:
What’s involved: Solenoid Barcode/QR Code Calibration Input & TCU Adaptive Relearn
Must write the 68-digit solenoid calibration code printed on the case barcode sticker into the TCU, perform a 'Resetting Auto T/A Values' command to clear old wear patterns, and execute a specific drive cycle. Arm 2 notes a TCM adaptive relearn is required to reset shift adaptation data.
Pro tips for a smooth first start-up — hand them to whoever does the install:
- Torque Converter Seating: Must ensure a 'three-click' fully recessed engagement (approx 11-12mm depth) before bolting to engine to avoid cracking the internal oil pump gear.
- Protect the Barcode Sticker: Do not spray brake cleaner, degreaser, or pressure wash the 68-digit sticker on top of the case. Take a photo immediately.
- Subframe Alignment: Dropping the front subframe is mandatory; use alignment pins or carefully align to the body to prevent throwing off wheel alignment.
- Fluid Level Check Procedure: No dipstick. Must fill, warm fluid to 122°F–140°F (50°C–60°C), and check via the overflow level plug on the front valve body cover while level and running in Park.
Easy to get right once you know them:
- Reusing the old torque converter, which introduces contaminated fluid and metal debris into the replacement unit.
- Using generic multi-vehicle ATF instead of the required Kia/Hyundai SP-IV or SP4M-1 fluid.
- Skipping the 68-digit solenoid calibration barcode programming, leading to immediate shift shock.
- Not replacing the front pump seal during installation despite known blowout issues.
- Skipping the professional transmission cooler and line flush.
- Buying the wrong 'A6' family transmission from a different engine application (e.g., Elantra or Forte) assuming it fits.
Not issues with the units on this page — the manufacturer documented these for every transmission of this family, wherever you buy one. Handy for your installer:
🔎 Recommended at install: Program the 68-digit barcode calibration values from the replacement transmission sticker into the vehicle's TCU.
🔎 Recommended at install: Update the ECU and TCU software logic.
🔎 Recommended at install: Install a new, updated OEM front pump seal before installing the transmission.
🔎 Recommended at install: Replace internal plastic wiring harness and fluid temperature sensor if cracked or high resistance develops.
🔎 Recommended at install: Update TCM software per Kia technical service bulletin.
🔎 Recommended at install: Complete transmission replacement.
🔎 Recommended at install: Avoid hard impacts; replace broken rear mount or cracked bellhousing.
Researched from factory recalls, TSBs and OEM service data (reference unit 400-63227-4321717). Unit-specific details — mileage, condition, warranty, freight — are covered in the checkout interview.
Policies, in plain English.
Shipping & Handling
- Ships by LTL freight on a pallet — a real freight truck, not a parcel van
- Your checkout freight quote covers delivery to your door (liftgate service included for residential addresses)
- The carrier calls ahead to schedule a delivery window — someone must be present to receive it
- Typically palletized and picked up within 2–3 business days; transit time depends on distance
120-Day Warranty
This part includes a 120-day warranty.
- If the part fails within the warranty window, we'll replace it or refund per the coverage terms
- Coverage is parts-only — installation labor is not included
- Warranty covers defects — not installation errors, misuse, or damage after installation
Your pre-purchase interview reviews these exact terms with you before anything is charged.
Returns (30 Days)
We accept returns of uninstalled parts within 30 days of delivery for this part.
- Defective parts: We will replace the part or issue a refund at our discretion
- Programming: "Needs to be programmed to my vehicle" is not a valid return reason. Many modules require dealer programming — we're happy to help connect you with resources if your dealer says it's not programmable
- Return shipping: This part ships by freight (LTL) — the part price is refundable per the terms above, but shipping costs are non-refundable and return freight follows the seller's return terms. Your pre-purchase interview walks through the exact numbers before you buy
- Parts must be returned in original packaging and unmodified condition
- Poorly packaged returns that arrive damaged will not be credited
Damaged in Shipping?
Freight damage is rare — and you're fully protected when you do two things at delivery:
- Inspect before you sign — you're allowed time to look the pallet over while the driver waits
- Write any damage on the delivery receipt before signing — that one line is what makes a freight claim succeed
- Severe damage? Refuse the delivery — it goes back at no cost to you and we make it right
- Photograph the pallet before unwrapping; report concealed damage within 24 hours of delivery
We handle the carrier claim — you just help document it. Your pre-purchase interview walks through this checklist too.
Order Cancellation
Cancel before shipment for a full refund. Once the pallet has been built, a preparation charge may apply — and once the freight carrier picks it up, shipping costs are non-refundable and standard return terms apply. Your pre-purchase interview shows the exact numbers before you pay.
Expert Guides
2016-2020 Kia Optima 2.4L A6MF2 Transmission: Problems, Identification, and Used Replacement
Identify common A6MF2 failures, decode your VIN, and learn exactly what to check before buying a used replacement transmission.
Read Full Guide →Related Trouble Codes (OBD-II)
4 matching guidesIf your scan tool is showing one of these trouble codes, this part is a common fix. Each guide explains the code, how to diagnose it, and exactly what to replace.
Miscellaneous Information
OEM Part Numbers:
Kia: 35440-39664, 450003BYE0, 450003BYE0R, 450003BYE0S, 9J1-615-301-B, A1679006018
Fits Years: 2016 2017 2018 2019 2020
Your Go-To Place
for auto parts.
In operation since 2007. Trusted by over a million DIYers, mechanics, and body shops across all 50 states.
Confirmed Before It Ships
Every freight order is confirmed through a short guided interview — fitment, condition, delivery and warranty terms, e-signed before you're charged.
Trusted Since 2007
Nearly two decades of shipping parts to professionals & enthusiasts.
Backed By The Selling Yard
This unit ships with the selling yard's 120-day warranty. Longer plans can be requested during checkout.
What buyers are saying.
Racing Partner Videos
