🔧 Sonata - Transmission Fluid Change (Drain & Fill)

On your Sonata, the DIY-friendly way to service the automatic transmission is usually a drain-and-fill. This replaces a large portion of the old fluid without requiring a machine flush, and it’s the safest approach for a first-timer.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a level surface and support the car with jack stands before going underneath.
• ⚠️ Transmission fluid can be hot—let it cool if you just drove.
• ⚠️ Your Sonata is a Plug-In Hybrid: avoid touching orange high-voltage cables and do not pry on HV components.
• ⚠️ Keep the car in PARK and chock the rear wheels.
• ⚠️ Battery disconnect is not required for a basic drain-and-fill.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Drain pan (at least 10-quart)
• Metric socket set (8mm-24mm)
• 3/8" drive ratchet
• 6" socket extension (3/8" drive)
• Torque wrench (10-80 ft-lbs range)
• Trim clip tool
• Flat-blade screwdriver
• Fluid transfer pump (specialty)
• Long funnel
• Shop rags

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Automatic transmission fluid (Hyundai ATF SP-IV) - Qty: 6 quarts
• Transmission drain plug crush washer - Qty: 1
• Transmission fill/level plug crush washer - Qty: 1
• Brake cleaner - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and place wheel chocks behind the rear tires.
• Gather fluid and supplies first—once you drain, you’ll want to refill right away.
• Look under the front of the car and identify which system you have:
  • Dipstick style: there’s a transmission dipstick under the hood.
  • Sealed style: no dipstick; it uses a fill/level plug on the transmission case.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Lift and support the front of the car

• Use a floor jack (rated 3-ton minimum) to lift the front at the proper jack point.
• Set the car down onto jack stands (rated 3-ton minimum).
• Give the car a gentle push to confirm it’s stable before going under.

Step 2: Remove the lower engine cover (if equipped)

• Use a metric socket set (8mm-24mm) with a 3/8" drive ratchet to remove the bolts.
• Use a trim clip tool and flat-blade screwdriver to remove any push clips.
• Set the cover and clips aside in a small pile. Keep clips with their holes.

Step 3: Locate the transmission drain plug and prepare to drain

• Position the drain pan (at least 10-quart) under the transmission drain plug.
• Clean the area around the plug using brake cleaner and shop rags.

Step 4: Drain the transmission fluid

• Use a metric socket set (8mm-24mm) with a 3/8" drive ratchet to loosen and remove the drain plug.
• Let it drain until it slows to an occasional drip.
• Install a new drain plug crush washer.
• Reinstall the drain plug and Torque to 44-49 Nm (32-36 ft-lbs).

Step 5: Refill (choose the correct path for your Sonata)

• Path A — If your Sonata has a dipstick:
  • Open the hood and remove the transmission dipstick.
  • Use a long funnel and pour in Hyundai ATF SP-IV slowly (start with about what you drained).
  • Reinsert the dipstick fully.
• Path B — If your Sonata is sealed (no dipstick):
  • Locate the transmission fill/level plug on the case.
  • Use a metric socket set (8mm-24mm) with a 3/8" drive ratchet to remove the fill/level plug.
  • Use a fluid transfer pump (specialty) to pump Hyundai ATF SP-IV into the fill hole until fluid begins to run back out.
  • Install a new fill/level plug crush washer.
  • Reinstall the plug and Torque to 39-49 Nm (29-36 ft-lbs).

Step 6: Circulate fluid and verify level

• Start the car and keep your foot on the brake.
• Shift slowly through P-R-N-D and back to P, pausing 2-3 seconds in each gear.
• Dipstick style: Use the dipstick to verify the level is within the marked range; add fluid through the funnel if needed.
• Sealed style: If you have the sealed setup, the most accurate level check is done at the specified fluid temperature; a shop-grade scan tool is typically used for this. If you don’t have that, do a careful drain-and-fill and recheck for leaks, then consider having a shop confirm final level.

Step 7: Reinstall the lower cover and lower the car

• Reinstall the under cover using the metric socket set (8mm-24mm), 3/8" drive ratchet, and trim clip tool.
• Use the floor jack (rated 3-ton minimum) to lift slightly, remove the jack stands (rated 3-ton minimum), then lower the car.

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✅ After Repair

• Test drive 10-15 minutes and confirm shifts feel normal (no slipping or flare).
• Park and check underneath for leaks around the drain plug and any fill/level plug.
• Recheck the level again (dipstick vehicles) after the drive, on level ground.
• Dispose of used ATF properly at a recycling center or parts store that accepts fluids.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $60-$130 (parts only)

You Save: $120-$350 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.