6-Speed Automatic Transmission Assembly for 2015-2016 Buick LaCrosse, Regal
Product Notes Read before buying
This is a 6-speed automatic transmission for Front-Wheel Drive models equipped with the 2.4L eAssist mild-hybrid engine only. It fits vehicles with GM option code MHH. Please verify this matches your vehicle's specifications before ordering.
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 |
|---|---|---|---|---|
| Base | Sedan | 2015 - 2016 | L4 2.4L MILD HYBRID EV-GAS (MHEV) | FWD | Automatic |
| Base | Sedan | 2015 - 2016 | V6 3.6L FLEX | FWD | Automatic |
| Leather | Sedan | 2015 - 2016 | L4 2.4L MILD HYBRID EV-GAS (MHEV) | AWD/FWD | Automatic |
| Leather | Sedan | 2015 - 2016 | V6 3.6L FLEX | AWD/FWD | Automatic |
| Premium | Sedan | 2015 - 2016 | V6 3.6L FLEX | AWD/FWD | Automatic |
| Base | Sedan | 2016 | V6 3.6L | FWD | Automatic |
| Leather | Sedan | 2016 | V6 3.6L | AWD/FWD | Automatic |
| Premium | Sedan | 2016 | V6 3.6L | AWD/FWD | Automatic |
| Sport Touring | Sedan | 2016 | V6 3.6L FLEX | FWD | Automatic |
| Sport Touring | Sedan | 2016 | V6 3.6L | FWD | Automatic |
| SubmodelSUB- MODEL |
Body Style | Years | Engine | Attributes |
|---|---|---|---|---|
| Base | Sedan | 2015 | L4 2.0L Turbo | AWD/FWD | Automatic |
| Base | Sedan | 2015 | L4 2.4L FLEX | AWD/FWD | Automatic |
| GS | Sedan | 2015 | L4 2.0L Turbo | AWD/FWD | Automatic & Manual |
| Premium | Sedan | 2015 | L4 2.0L Turbo | AWD/FWD | Automatic |
| Premium | Sedan | 2015 | L4 2.4L MILD HYBRID EV-GAS (MHEV) | AWD/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 RPO Codes: Confirm 'MHH' and 'LUK' on the Service Parts Identification sticker in the glove box or trunk.
- Check VIN 8th Digit: Confirm it is 'R' (designating the 2.4L eAssist hybrid engine).
- Verify Original Transmission Tag: Confirm the 4-character code is '5CCW' (or compatible supercession like 4CCW).
- Confirm Drivetrain: Verify the vehicle is Front-Wheel Drive (FWD).
What the install really takes — plan and budget with confidence:
Special tools this job needs:
- Engine support fixture
- Transmission jack
- Torque converter lifting/alignment handles (GM tool J-46409 or DT-46409)
- GM-compatible J2534 programming interface with GM SPS2 subscription
Budget for these consumables at install:
- DEXRON-VI Full Synthetic automatic transmission fluid (approx. 8.0 to 9.0 quarts for dry fill)
- Torque converter input seal (GM Part # 24230687)
- CV axle seals (both sides)
- New auxiliary fluid inlet pump seal
- Professional-grade transmission cooler line flush
What your vehicle’s computers will need after the swap:
What’s involved: VIN-Specific Flash Programming and Transmission Adaptive Values Learn
The integrated TEHCM is programmed with the donor vehicle's VIN and will cause a security mismatch/theft-lock or severe shifting issues if not reprogrammed. Alternatively, the original TEHCM can be swapped into the replacement transmission if functioning. A Transmission Adaptive Values Learn must be performed regardless of the method used.
Pro tips for a smooth first start-up — hand them to whoever does the install:
- Torque Converter Seating: Must feel/hear three distinct drops/clicks as it engages. Failing to fully seat the converter will crush and destroy the transmission oil pump instantly upon tightening the bellhousing bolts.
- The Cold-Fluid Level Trap: Below 140°F (60°C), the internal bimetal thermostatic fluid level control valve allows fluid to drain back into the sump. Fluid level must be checked only when fluid temperature is between 185°F and 203°F (85°C to 95°C) with the engine idling in Park on a level surface.
- Subframe Alignment: Front subframe must be marked or aligned precisely during reinstallation to prevent steering and suspension geometry issues.
- Dowel Pins: Ensure alignment dowel pins are present and clean on the engine block before mating the transmission.
Easy to get right once you know them:
- Ordering for a non-hybrid vehicle (must have the eAssist system, RPO code MHH, and VIN 8th digit 'R').
- Skipping the VIN programming of the internal TEHCM.
- Reusing the old auxiliary pump seals when swapping the original pump.
- Checking fluid level on an angle instead of a perfectly level surface.
- Improper torque converter installation leading to a broken fluid pump.
- Not flushing the transmission cooler lines, introducing old debris into the replacement unit.
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: Install an updated Teflon-coated replacement bushing and new seal during installation.
🔎 Recommended at install: Replace TEHCM or clean solenoids; ensure thorough cooler line flush to prevent debris contamination.
🔎 Recommended at install: TCM software update.
🔎 Recommended at install: Replace auxiliary electric pump internal seals or the electric motor.
🔎 Recommended at install: Ensure torque converter is fully seated during installation to prevent pump damage.
🔎 Recommended at install: Replace internal 3-5-R clutch wave plate.
🔎 Recommended at install: Perform fluid flush or replace torque converter clutch.
Researched from factory recalls, TSBs and OEM service data (reference unit 400-05008-2022444). 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
2015-2016 LaCrosse & Regal 2.4L 6T40 (MHH): Problems, Identification, and Used Replacement
Identify the exact eAssist transmission variant, understand common TEHCM and wave plate failures, and learn when to swap in a used OEM assembly.
Read Full Guide →Related Trouble Codes (OBD-II)
7 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:
GM: 19332240, 24262608
Other: 5CCW
Fits Years: 2015 2016
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This unit ships with the selling yard's 120-day warranty. Longer plans can be requested during checkout.
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