Transmission Assembly for 2013-2014 Buick & Chevrolet • Encore, Sonic, Trax - Front
Product Notes Read before buying
This is a 6-speed automatic transmission for front-wheel drive (FWD) vehicles with the 1.4L turbo engine. For the Chevrolet Sonic, this part fits the RS trim only. It has a final drive ratio of 3.53 (GM option code FXH). This unit may require programming by a qualified technician to ensure proper function.
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 | SUV | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic |
| Convenience | SUV | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic |
| Leather | SUV | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic |
| Premium | SUV | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic |
| SubmodelSUB- MODEL |
Body Style | Years | Engine | Attributes |
|---|---|---|---|---|
| RS | Hatchback | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic | Hollander: SONIC 13-14 AT; 1.4L, RS; drive_type: include FWD; engine_size: include 1.4L; aspiration: include TURBO; transmission: include Automatic [inferred] |
| SubmodelSUB- MODEL |
Body Style | Years | Engine | Attributes |
|---|---|---|---|---|
| LS | SUV | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic |
| LT | SUV | 2013 - 2014 | L4 1.4L Turbo | FWD | Automatic |
| LTZ | SUV | 2013 - 2014 | L4 1.4L Turbo | 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 the 8th digit of the VIN is 'B' (designates the 1.4L Turbo engine).
- Confirm the vehicle is Front-Wheel Drive (FWD) by checking for the absence of a rear differential and driveshaft.
- Locate the RPO code 'MH8' on the Service Parts Identification sticker (in the glove box or trunk/spare tire cover).
- Check the transmission identification tag on the original case to match codes 3GJW, 3HJW, or 3SAW.
What the install really takes — plan and budget with confidence:
Special tools this job needs:
- Engine support bar
- Transmission jack
- GM-compatible bi-directional scan tool (GDS 2 or equivalent)
- J2534 pass-through programming device (optional for DIY programming)
Budget for these consumables at install:
- DEXRON-VI Full Synthetic ATF (6 to 7 quarts for standard swap, 9 to 10 quarts for full system flush/dry overhaul)
- Torque converter seal (front pump seal)
- Left and right axle shaft seals
- Side cover gasket (if swapping original TEHCM)
- Aerosol transmission cooler flush solvent (e.g., Lubegard Kooler Kleen)
What your vehicle’s computers will need after the swap:
What’s involved: VIN programming and Transmission Adaptive Values Learn (Fast Learn)
The internal TEHCM is locked to the donor vehicle's VIN. You must either program the replacement TEHCM to your vehicle's VIN using GM Service Programming System (SPS2) software, or swap your original working TEHCM into the replacement unit. Regardless of the option chosen, a Transmission Service Fast Learn (adaptive reset) must be performed using a GM-compatible scan tool.
Pro tips for a smooth first start-up — hand them to whoever does the install:
- Torque Converter Seating: Must spin and push the converter until it fully engages and clicks three distinct times. If not fully seated, bolting the transmission to the engine will shatter the front pump.
- No-Dipstick Fluid Level Check: Must check fluid level only when the fluid temperature is between 85°C and 95°C (185°F to 203°F) with the engine idling and the vehicle level, using the check plug on the side of the case.
- Cooler Line Flush: Must thoroughly flush the cooler lines to prevent old debris from contaminating the replacement unit's sensitive solenoids.
- Adaptive Relearn: The vehicle may shift harshly or erratically until the adaptive learn procedure is performed and followed by a specific drive cycle.
Easy to get right once you know them:
- Ordering FWD for an AWD Vehicle: AWD transmissions have an entirely different case casting to accommodate the transfer case.
- Failing to Program or Swap the TEHCM: Results in a no-crank condition or immediate limp mode.
- Checking Fluid with the Engine Off: Causes several quarts of fluid to dump out of the check plug, leading to severe underfilling.
- Reusing a Contaminated Torque Converter: Trapped metal shavings from the old failed transmission will contaminate and destroy the replacement unit.
- Skipping the Cooler Line Flush: Allows trapped debris to flow directly into the replacement unit's solenoids.
- Using the Wrong Fluid: Using generic or incorrect fluid instead of licensed DEXRON-VI can cause persistent shifting problems.
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: Verify the axle bushing inside the case is tight before installing and replace the axle seal.
🔎 Recommended at install: Check for a faulty ground, wiring harness chafing, or internal failure of the TEHCM.
🔎 Recommended at install: Update the TCM software calibration to refine the adaptive learning tables.
🔎 Recommended at install: GM updated the wave plate design for the Gen 2 unit, but it remains a well-known historical failure point.
🔎 Recommended at install: Dealers are to replace the transmission turbine shaft.
🔎 Recommended at install: Can cause shuddering or vibration during light acceleration; inspect/replace torque converter.
Researched from factory recalls, TSBs and OEM service data (reference unit 400-04876-2124180). 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
2013-2014 Trax, Encore & Sonic 6T40 Transmission: Problems, Identification, and Used Replacement
Identify the correct Gen 2 6T40, understand common failures like turbine shaft fractures, and learn when to replace it with a used OEM unit.
Read Full Guide →Related Trouble Codes (OBD-II)
14 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: 24265813
Other: 3GJW, 3HJW, 3SAW
Fits Years: 2013 2014
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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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