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2018 Hyundai Sonata
2018 Hyundai Sonata
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How to Replace a Gas Cap on a 2014 - 2018 Hyundai Sonata

How to Replace a Gas Cap on a 2014 - 2018 Hyundai Sonata

Suggested Parts

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Tools & Fluids

Nitrile
Nitrile
Gloves
Safety
Safety
Glasses
Cloth Rags
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How to Replace the Fuel Cap on a 2018 Hyundai Sonata (Fix EVAP Leak & Check Engine Light)

Step-by-step fuel cap replacement with tools, correct tightening clicks, safety tips, and EVAP leak troubleshooting

How to Replace the Fuel Cap on a 2018 Hyundai Sonata (Fix EVAP Leak & Check Engine Light)

Step-by-step fuel cap replacement with tools, correct tightening clicks, safety tips, and EVAP leak troubleshooting

Orion
Orion

šŸ”§ Sonata - Fuel Cap Replacement

Replacing the fuel cap on your Sonata is a quick job: you remove the old cap and install a new one that seals correctly. A good seal prevents fuel vapor leaks and helps avoid a check-engine light related to the EVAP (fuel vapor) system.

Difficulty Level: Beginner | Estimated Time: 0.1-0.3 hours


āš ļø Safety & Precautions

  • āš ļø Work in a well-ventilated area—fuel vapors are flammable.
  • āš ļø No smoking, flames, or hot work near the fuel door.
  • āš ļø Turn the car OFF before opening the fuel cap.
  • āš ļø If you smell strong fuel odor after replacement, stop and re-check the seal.

šŸ”§ Required Tools

You'll need the following tools for this repair:

  • Nitrile gloves
  • Safety glasses
  • Clean shop towel

šŸ”© Required Parts

HowToo sells all the parts you need for this repair:

  • Fuel cap (EVAP-sealing type) - Qty: 1

šŸ“‹ Before You Begin

  • Park on level ground and make sure the car is completely OFF.
  • Let the car sit 1–2 minutes if it was just driven, so tank vapors settle.
  • Have a clean shop towel ready to wipe the filler neck sealing area.

šŸ”Ø Step-by-Step Instructions

Follow these steps in order:

Step 1: Open the fuel door

  • Use your hand to open the fuel door on the left-rear quarter panel.
  • Put on nitrile gloves and safety glasses.

Step 2: Remove the old fuel cap

  • Turn the cap counterclockwise by hand until it releases.
  • If the cap has a tether (a small strap that keeps it attached), let it hang without twisting the strap.
  • If you hear a hiss, that can be normal.

Step 3: Inspect and clean the sealing surfaces

  • Use a clean shop towel to wipe the filler neck sealing lip (the smooth surface where the cap’s gasket seals).
  • Check the old cap’s rubber gasket for cracks or flattening—this is a common cause of EVAP leak codes.

Step 4: Install the new fuel cap

  • Thread the new cap on by hand clockwise.
  • Tighten until it clicks several times (typically 1–3 clicks) and feels fully seated.
  • If there’s a tether, make sure it isn’t pinched and the cap hangs naturally when removed.

Step 5: Close the fuel door

  • Close the fuel door firmly by hand until it latches.

āœ… After Repair

  • Start the car and confirm there’s no fuel smell around the fuel door.
  • If you were replacing the cap due to a check-engine light, it may take several drive cycles to clear on its own.
  • If the light stays on, the car may need the code cleared with a scan tool and the EVAP system checked for other leaks.

šŸ’° DIY vs Shop Cost

Shop Cost: $30-$90 (parts + labor)

DIY Cost: $15-$45 (parts only)

You Save: $15-$45 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.2-0.5 hours.


šŸŽÆ 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.

Guide for Fuel Tank Cap replace for these Hyundai vehicles

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2018 Hyundai Sonata
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