2021 Ford F-350 Super Duty — Key Fob Programming

Quick reference

Step-by-step on-board programming

Your 2021 F-350 uses Ford’s PATS immobilizer. DIY programming is only possible to add a third key/fob when you already have two distinct, working, programmed keys/fobs for the truck. If you have fewer than two, skip to the “If on-board programming isn’t supported” section.

There are two factory configurations on this model year. Follow the steps that match your truck.

A) Turn-key ignition (integrated key with buttons)

1. Have all three keys present: the two existing working keys and the new unprogrammed key. The new key’s blade must be cut to the truck first.
2. Insert Working Key 1 and turn the ignition to RUN (do not start). Leave it ON ~3 seconds, then turn OFF and remove.
3. Within 10 seconds, insert Working Key 2 and turn to RUN for ~3 seconds, then turn OFF and remove.
4. Within 20 seconds, insert the new key and turn to RUN. The security light should illuminate then go out after a few seconds, indicating successful programming.
5. Test: start the engine with the new key and verify remote lock/unlock. If it doesn’t start, repeat from Step 2. Timing is critical.

B) Push-button start (Intelligent Access proximity fob)

1. Have both existing working fobs and the new unprogrammed fob. Cut the emergency key blade inside the new fob.
2. Locate the vehicle’s backup key/fob slot (often in the center console or under the cup holders—see owner’s manual Location of the passive key backup). The truck must detect fobs in this slot to program.
3. Place Working Fob 1 in the backup slot. Without pressing the brake, press the START/STOP button once. Wait for a chime or the cluster to acknowledge.
4. Remove Fob 1. Within 10 seconds, place Working Fob 2 in the backup slot and press START/STOP again (no brake). Wait for acknowledgement.
5. Remove Fob 2. Within 10 seconds, place the new, unprogrammed fob in the backup slot. Press START/STOP again (no brake). Wait for the dash message confirming programming (for example, “Key Programmed” or an updated key count).
6. Test: start the truck with the brake applied and verify remote functions.

Notes:

• If any step fails, restart the sequence. All timing windows are short by design for security.
• Remote lock/unlock functions pair automatically during immobilizer programming on these models.

If your truck does not enter programming mode, or you have only one or zero working keys/fobs, you’ll need a dealer or automotive locksmith with a capable scan tool to perform PATS programming.

Battery replacement

• Proximity fob (push-button):

  1. Slide out the emergency key. Use the metal blade or a plastic pry tool at the seam to carefully separate the case.
  2. Note battery orientation, then replace with a CR2032 cell. Avoid touching the cell surfaces.
  3. Snap the case back together and reinstall the emergency blade. No reprogramming required after a battery swap.

• Integrated key with buttons (turn-key):

  1. If equipped with a small screw on the back, remove it; otherwise, pry gently at the seam.
  2. Replace the coin cell (commonly CR2032) observing polarity.
  3. Reassemble and test the buttons.

Where to buy a replacement fob

• Ford dealer

  • Pros: Guaranteed correct part by VIN; latest superseded part numbers; firmware/feature match.
  • Cons: Highest price; programming charges apply.
  • Typical totals: OEM proximity fob $180–$350 plus $100–$180 programming. Integrated key $90–$180 plus $80–$140 programming and $10–$40 cutting.

• Automotive locksmith

  • Pros: Mobile service; lower labor than dealer; can cut and program on-site; can work with OEM or quality aftermarket.
  • Cons: Parts selection varies; must confirm FCC ID/VIN in advance.
  • Typical totals: Aftermarket proximity $60–$140, programming $80–$150; integrated key $35–$80, cutting $10–$40, programming $80–$140.

• Online (Amazon/eBay/marketplaces)

  • Pros: Lowest part cost; wide selection including refurbished OEM.
  • Cons: Easy to buy the wrong FCC ID; seller quality varies; you still need cutting/programming; returns can be a hassle.
  • Tip: Only buy listings that publish the exact FCC ID and support returns. Verify by VIN or by reading the label on your current fob.

If on-board programming isn’t supported

2021 Super Duty uses Ford’s PATS immobilizer (80-bit transponder for keyed ignitions; integrated immobilizer in proximity fobs). When you have fewer than two working keys/fobs, the vehicle requires a scan tool session (Ford IDS/FDRS or equivalent) with in-vehicle security access. During this process, all recognized keys are typically erased and re-added, so bring every key/fob you want to keep active.

• Expected costs: $150–$300 total with a locksmith using aftermarket/OEM parts; $280–$500+ at the dealer with OEM parts. Time on site is commonly 20–45 minutes once connected.
• What to bring: Proof of ownership and a photo ID. Many providers won’t proceed without them.
• Cutting: Turn-key trucks need the blade cut before programming; push-button trucks need the emergency blade cut for glovebox/door access and as a backup start method.

Always match FCC ID and button layout to your truck’s build (keyed vs. push-button, remote start, tailgate/rear glass options). When in doubt, provide your VIN to a dealer or locksmith.

Find a mobile locksmith or shop on Repairius.