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2021 Jeep Gladiator
2020 - 2023 Jeep Gladiator
V6 3.6L
Compatible with more variants.

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Jeep “Check gas cap” Fix - Full repair

Jeep “Check gas cap” Fix - Full repair

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Nitrile
Nitrile
Gloves
Paper Towels
Paper Towels
Trim
Trim
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Flashlight
Flashlight
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How to Replace the Fuel Cap on a 2021 Jeep Gladiator (Fix EVAP Leak & Check Engine Light)

Step-by-step instructions with required tools/parts, safety tips, and what to do if the CEL returns for 2020, 2021, 2022, 2023

How to Replace the Fuel Cap on a 2021 Jeep Gladiator (Fix EVAP Leak & Check Engine Light)

Step-by-step instructions with required tools/parts, safety tips, and what to do if the CEL returns for 2020, 2021, 2022, 2023

Orion
Orion

🔧 Gladiator - Fuel Cap Replacement

Replacing the fuel cap on your Gladiator is a quick job: you remove the old cap and install a new one that seals correctly. A good seal helps prevent fuel vapor leaks, check-engine lights, and fuel smell.

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


⚠️ Safety & Precautions

  • ⚠️ Work outside or in a well-ventilated area away from flames or smoking.
  • ⚠️ Turn the engine OFF before opening the fuel door.
  • ⚠️ If you smell strong fuel, stop and let vapors clear.
  • ⚠️ No battery disconnect is required for this repair.

🔧 Required Tools

You'll need the following tools for this repair:

  • Nitrile gloves
  • Clean shop towel
  • Plastic trim tool (specialty)
  • Flashlight

🔩 Required Parts

HowToo sells all the parts you need for this repair:

  • Fuel filler cap (gas cap) for Gladiator - Qty: 1

📋 Before You Begin

  • Park on level ground and shut the engine off.
  • Let the truck sit 1-2 minutes if you just drove it.
  • Open the fuel door and wipe around the filler opening with a clean shop towel.

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open the fuel door

  • Open the fuel door by hand.
  • Use a flashlight to look for dirt or damage around the filler neck (the metal tube you fuel through).

Step 2: Remove the old fuel cap

  • Turn the cap counterclockwise by hand until it releases.
  • If your cap has a tether (the small strap that keeps it from getting lost), let it hang without twisting it.
  • If it’s stuck, turn slowly and steadily.

Step 3: Inspect and clean the sealing area

  • Use a clean shop towel to wipe the sealing surface on the filler neck (the smooth ring the cap seals against).
  • Look at the old cap’s rubber seal (the gasket). If it’s cracked, flattened, or missing, that can cause an EVAP leak and a check-engine light.

Step 4: Transfer the tether (if required)

  • If the new cap does not include a tether and your old cap uses one, move it over carefully.
  • Use a plastic trim tool (specialty) to gently pry the tether clip loose if it’s clipped to the cap. (A plastic trim tool is a non-metal pry tool that helps prevent scratches.)
  • Do not use a metal screwdriver here—it's easy to damage the plastic.

Step 5: Install the new fuel cap

  • Thread the new cap on by hand, turning clockwise.
  • Tighten until you feel it fully seat; if it’s a ratcheting-style cap, keep turning until it clicks a few times.
  • Start threads gently to avoid cross-threading.

Step 6: Close the fuel door

  • Close the fuel door firmly by hand.
  • Use a flashlight to confirm the cap is seated and the tether (if equipped) isn’t pinched.

✅ After Repair

  • Start the engine and verify there’s no fuel smell around the fuel door.
  • If you had a check-engine light for a loose cap, it may take a few drive cycles to clear on its own.
  • If the light stays on, you’ll likely need the code read—an EVAP leak can have other causes besides the cap.

💰 DIY vs Shop Cost

Shop Cost: $40-$120 (parts + labor)

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

You Save: $25-$75 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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