2021 Ford F-150 — Key Fob Programming

Quick reference

Item	Detail
FCC ID	Varies by trim/options. Check the label on the back of your current fob or inside the fob case.
OEM Fob PN	Varies by VIN/feature set (remote start, power tailgate, etc.). Dealer can confirm by VIN.
Aftermarket Options	Refurbished OEM smart keys and compatible aftermarket proximity fobs are available; verify exact FCC ID/feature match before purchase.
Battery Type	CR2450 coin cell in most 2021 F-150 smart keys (some variants may use CR2032 — verify by opening the fob or checking the owner’s manual).
Programmable On-Board?	Conditional. Adding a spare may be possible on-board only if you already have two working admin keys. Otherwise, programming requires a dealer/locksmith scan tool.
Cuts Required?	Yes — the emergency key blade inside the fob must be cut to your truck.

Step-by-step on-board programming

Important: 2021 F-150 uses Ford’s PATS immobilizer and a Radio Frequency Hub/Remote Function Actuator. As a rule, on-board programming is only possible to add a spare when you already have two working admin keys/fobs. If you have zero or one working key, you will need a professional scan tool.

Before you begin

• Locate the backup starting slot (also called the passive key backup location). On many F-150s it’s inside the center console or front bin. Your owner’s manual shows the exact location and orientation for the fob in the slot.
• Have two working admin keys/fobs present, plus the new unprogrammed fob.

A) Vehicles with push-button start (proximity “smart” key)

1. Place Working Key 1 in the backup slot. Do not press the brake.
2. Press the START/STOP button once to turn the ignition on (no engine start), then press again to turn it off. Remove Key 1.
3. Place Working Key 2 in the backup slot.
4. Press START/STOP once to turn ignition on, then off. Remove Key 2.
5. Within 10 seconds, place the new unprogrammed fob in the backup slot.
6. Press START/STOP once. Wait for a chime/message indicating the key is programmed. Remove the new fob.
7. Test: With the new fob in the vehicle, press brake and START to confirm engine starts. Test lock/unlock and remote start (if equipped).

Notes:

• If the vehicle displays “Maximum number of keys learned” or fails to enter programming, you’ll need a scan tool to erase/relearn keys.
• Used fobs may be “locked” to a previous vehicle and will not program unless properly reset by a professional.

B) Vehicles with keyed ignition (if equipped on certain XL/XLT configurations)

1. Insert Working Key 1. Turn to ON (RUN) for 3 seconds, then OFF and remove.
2. Within 10 seconds, insert Working Key 2. Turn to ON for 3 seconds, then OFF and remove.
3. Within 10 seconds, insert the new unprogrammed transponder key and turn to ON. The security light should illuminate, then go out, confirming programming.
4. Test engine start and, if you have a separate remote transmitter, note that the remote portion typically cannot be self-programmed on 2011+ Fords and will require a scan tool.

If these sequences don’t work or you do not have two working admin keys, programming must be performed with Ford IDS/FDRS or a capable locksmith tool.

Battery replacement

1. Slide the release and remove the emergency key blade.
2. Use a thin flat tool in the seam/notch to gently pry the case apart.
3. Note battery orientation. Most 2021 F-150 fobs use a CR2450; some variants use a CR2032. Match the original.
4. Install the new coin cell without touching both faces (oils can shorten life). Positive side typically faces up.
5. Snap the case together, reinstall the blade, and test lock/unlock.

Where to buy a replacement fob

• Dealer: New OEM fob matched by VIN; guaranteed feature match. Typical parts cost $220–$450 for proximity fobs; programming $100–$180. Highest confidence, highest cost.
• Automotive locksmith: Mobile service, OEM or high-quality aftermarket/refurb options. Typical fob $150–$350; programming $80–$150. Can cut the emergency blade on-site.
• Online (Amazon/eBay): Aftermarket or refurbished OEM $60–$180. Verify the FCC ID and features (remote start, tailgate, panic). Risk of receiving a used/locked or incompatible unit. You will still need cutting and programming.

Tip: Always match by FCC ID on your original fob and confirm options. For proximity keys, avoid used units unless a seller certifies they are professionally “unlocked”/reset.

If on-board programming isn’t supported

• Why: The 2021 F-150 uses Ford PATS with an integrated immobilizer transponder in the smart key. The Remote Function Actuator pairs encrypted rolling codes with the BCM; access requires security credentials (in-code/out-code) via Ford IDS/FDRS or a locksmith tool.
• What to expect: A professional will perform a security login, erase or add keys, and pair the transmitter. Plan 15–45 minutes on-site plus key cutting for the emergency blade. If all keys are lost, expect a full key erase and relearn (all existing fobs must be reintroduced).
• Costs: All-keys-lost events typically run $250–$500 total with a locksmith, $350–$650 at the dealer, depending on parts and your option set. Adding a spare when you already have one working key is usually $120–$250 with a locksmith plus the fob cost.

Notes on blades and transponders

• The emergency key blade inside the fob must be cut to your truck. Bring proof of ownership for cutting and programming.
• The immobilizer transponder is integrated in the smart key and uses Ford’s high-security PATS (80-bit). Cloning is limited and not recommended on this platform; proper programming is preferred.

Find a mobile locksmith or shop on Repairius.