How to Replace the Fuel Cap on a 2016 Ford Flex (Fix EVAP Leaks & Check Engine Light)
Step-by-step fuel cap replacement with tools, parts, sealing tips, and what to expect after the repair
How to Replace the Fuel Cap on a 2016 Ford Flex (Fix EVAP Leaks & Check Engine Light)
Step-by-step fuel cap replacement with tools, parts, sealing tips, and what to expect after the repair
š§ Flex - Fuel Cap Replacement
Replacing the fuel cap is a quick job that helps prevent fuel vapor leaks and āCheck Engineā lights caused by an EVAP (fuel vapor) leak. On your Flex, itās a simple twist-off/twist-on part, but getting the seal right matters.
Difficulty Level: Beginner | Estimated Time: 0.1-0.3 hours
ā ļø Safety & Precautions
- ā ļø Work in a well-ventilated area and keep away from sparks/flames.
- ā ļø Turn the engine OFF before opening the fuel door.
- ā ļø Do not top off the tank after the pump clicks off.
- Battery disconnect is not required.
š§ Required Tools
You'll need the following tools for this repair:
- Nitrile gloves
- Shop towel
- Flashlight
š© Required Parts
HowToo sells all the parts you need for this repair:
- Fuel cap (OE-equivalent, tethered) - Qty: 1
š Before You Begin
- Park on level ground and shift to Park.
- Shut the engine off and wait 30 seconds to let vapors settle.
- Wipe dirt around the fuel filler opening using a shop towel so debris doesnāt fall in.
šØ Step-by-Step Instructions
Follow these steps in order:
Step 1: Open the fuel door
- Open the fuel door on the rear quarter panel.
- Use a flashlight to check for dirt or damage around the filler area.
Step 2: Remove the old fuel cap
- Put on nitrile gloves.
- Turn the cap counterclockwise until it releases, then pull it away from the filler neck.
- If your cap has a tether (a small retaining strap), let it hang freely.
Step 3: Inspect and clean the sealing area
- Use a shop towel to wipe the filler neck sealing surface (the smooth ring where the cap seals).
- Make sure there are no cracks, deep nicks, or stuck-on debris.
- Clean seal = no EVAP leak.
Step 4: Install the new fuel cap
- Align the new cap and turn it clockwise by hand.
- Continue turning until you feel/hear it click multiple times (typically 1ā3 clicks).
- Do not use tools to tighten; hand-tight only.
Step 5: Close the fuel door
- Close the fuel door fully until itās flush with the body.
- Use a flashlight for a quick final check that the cap sits straight.
ā After Repair
- Start the engine and verify thereās no fuel smell near the fuel door.
- If you had a āCheck Engineā light for an EVAP leak, it may take a few normal drive cycles to turn off on its own after the cap is sealing correctly.
- If the light stays on, the issue may be a different EVAP leak (not the cap).
š° DIY vs Shop Cost
Shop Cost: $40-$120 (parts + labor)
DIY Cost: $15-$35 (parts only)
You Save: $25-$85 by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.2-0.4 hours.
šÆ 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.
















