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2018 Hyundai Ioniq
2017 - 2018 Hyundai Ioniq
Inline 4 1.6L

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Fuel Tank Cap - Fits Various Hyundai Vehicles

Fuel Tank Cap - Fits Various Hyundai Vehicles

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Tools & Fluids

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

Step-by-step fuel cap replacement with tools, parts, safety tips, and seal checks to prevent EVAP codes for 2017, 2018

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

Step-by-step fuel cap replacement with tools, parts, safety tips, and seal checks to prevent EVAP codes for 2017, 2018

Orion
Orion

🔧 Ioniq - Fuel Cap Replacement

Replacing the fuel cap on your Ioniq is a quick job: you remove the old cap from the tether (the little retention strap) and install a new cap that seals correctly. A good seal is important because a loose or wrong cap can trigger an EVAP leak warning and sometimes a check engine light.

Difficulty Level: Beginner | Estimated Time: 0.1-0.2 hours


⚠️ Safety & Precautions

  • ⚠️ Turn the car OFF and keep sparks/flames away from fuel vapors.
  • ⚠️ Don’t top off after the pump clicks off; it can damage the EVAP system.
  • ⚠️ If you smell strong fuel odor after replacement, stop and re-check the seal.
  • Battery disconnect is not required.

🔧 Required Tools

You'll need the following tools for this repair:

  • Nitrile gloves
  • Clean shop towel
  • Flashlight

🔩 Required Parts

HowToo sells all the parts you need for this repair:

  • Fuel cap (capless-compatible is NOT used on Ioniq) - Qty: 1

📋 Before You Begin

  • Park on level ground and switch the car OFF.
  • Open the fuel door and have a clean shop towel ready to wipe the sealing surface.
  • If your Ioniq has a tethered cap (most do), locate the tether connection point on the fuel door area.

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the old fuel cap

  • Open the fuel door.
  • Turn the fuel cap counterclockwise until it releases, then remove it.
  • Use a flashlight to look at the filler neck opening and sealing rim.

Step 2: Disconnect the tether (if equipped)

  • The tether is the small strap that keeps the cap from getting lost.
  • Use your fingers (or a clean shop towel for grip) to slide the tether loop off its tab, or gently unclip it if it’s a clip style.
  • Don’t yank—tethers tear easily.

Step 3: Clean the sealing surface

  • Use a clean shop towel to wipe the filler neck sealing rim (where the cap’s rubber seal contacts).
  • Wipe away dirt/sand so the new cap can seal properly.

Step 4: Install the new fuel cap

  • Attach the new cap to the tether the same way the old one was attached.
  • Insert the cap into the filler neck and turn clockwise until you hear/feel it click and stop.
  • Close the fuel door.

Step 5: Verify the seal

  • Re-open the fuel door and confirm the cap is fully seated and tight (clicked).
  • Use a flashlight to confirm the cap sits square and the seal isn’t pinched.

✅ After Repair

  • If you had a check engine light from a loose cap, it may take a few drive cycles to clear on its own after the system re-tests.
  • If the light stays on after a few days of normal driving, the cap may be incorrect or the filler neck seal/EVAP system may have another leak.
  • Sniff-check around the fuel door area after your next fill-up; there should be no strong fuel smell.

💰 DIY vs Shop Cost

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

DIY Cost: $15-$40 (parts only)

You Save: $15-$50 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.1-0.2 hours.


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