GMC Sierra Denali & AT4 Proximity Spare Key in Granbury, TX

The cheapest key you will ever buy for a 2019-or-newer Sierra is the one you have made while the original still works. The most expensive is the one you need at 9 PM on a gravel road off FM 4 with no spare in existence. Call or text (817) 214-2934 and we will make the cheap one this week.

Quick Answer

A spare proximity fob for a GMC Sierra Denali, AT4, SLT, or any push-button-start Sierra can be programmed at your Granbury location, usually in under an hour. As of July 2026, spare smart-key work in Hood County runs roughly $150–$350 depending on the fob, versus a substantially higher all-keys-lost call plus the risk of a stranded truck. If you have one working fob today, this is a scheduled, inexpensive job.

Why the Denali and AT4 Trims Change the Job

"Sierra" covers two very different key systems, and the trim tells you which one you have.

Work-spec and lower trims frequently run a bladed transponder key with a separate remote, or a flip key. Programming these is a simpler, cheaper procedure.

Denali, AT4, and higher SLT builds on the 2019-and-newer T1 platform run push-button start with a proximity fob. There is no key slot in the column. The fob talks to the truck's keyless-entry system over RF, the truck detects it inside the cabin, and the start button works. Inside that fob is also a hidden emergency blade that opens the driver's door if the fob battery dies.

The practical differences for a spare:

• The fob itself is a more expensive part than a blade key.
• Programming requires diagnostic access to the truck's keyless-entry system, not a simple on-board key cycle.
• The emergency blade has to be cut to your truck, or the "dead fob" backup does not work.
• Most Sierras support a limited number of paired fobs, so an owner who has accumulated several over the years may need existing ones cleared.

If you are not certain which system your truck uses: look for a start button and no key cylinder in the column. That is proximity. Tell us that when you call and the quote will be right the first time.

What a Spare Actually Costs vs. All-Keys-Lost

Hood County ranges as of July 2026. The gap between rows one and three is the entire argument of this article. A dealer alternative for the same work typically runs $200–$600 or more and requires the truck at their service drive — our mobile pricing generally lands 40–60% below dealer for equivalent key services.

The Rural-Radius Argument for a Second Fob

In a dense suburb, losing your only key is annoying. In Hood County it is a logistics event.

Sierras around Granbury do not spend their lives in driveways. They tow boats to the ramps on both sides of the lake, pull stock trailers out to pasture gates, sit at deer leases past Bluff Dale, and park at job sites where the nearest cross street is a mile of caliche away. Four things get materially worse when the failure happens out there:

Drive time. Our response window to Tolar, Lipan, Nemo, or the Glen Rose edge is longer than to a house on the square. That is physics, not service quality — the Hood County response-time guide breaks it down by community.

Address ambiguity. A pasture gate has no street number. Every minute spent describing where you are is a minute the truck is still dead.

The load. A Sierra hitched to a gooseneck or a loaded boat trailer cannot simply be left. Whatever the solution is, it has to happen where the truck sits.

Water. Lake Granbury eats fobs. A fob that goes off a dock or into the water at a ramp is not coming back, and unlike a blade key, it cannot be improvised.

A spare fob costs a fraction of the emergency version of that same day, and it converts a stranding into an inconvenience.

How We Program a Sierra Spare on Site

1. Verify the truck and the owner. Texas locksmiths operate under the Texas Department of Public Safety Private Security Program, and ownership verification is part of the job. Registration, title, or insurance in your name plus matching photo ID. For company trucks, the registration in the business name plus your ID, or a fleet letter.
2. Confirm the system. Year, trim, push-button versus key slot, and how many fobs currently exist.
3. Source the correct fob. GM part families vary by year and equipment. The wrong fob will not pair no matter how good the tooling is.
4. Cut the emergency blade. Originated from the VIN so the mechanical backup actually opens the door.
5. Pair the fob to the keyless-entry system using diagnostic access. Where the truck's security gateway requires credentialed access, that runs through the National Automotive Service Task Force Vehicle Security Professional system — the same sanctioned channel a dealer technician uses.
6. Test everything. Lock, unlock, remote start if equipped, passive entry at each door, start from inside, and the dead-battery backup procedure. We show you how the backup works before we leave, because the moment you need it is not the moment to learn it.

Total time on site for a straightforward spare is typically 30 to 60 minutes.

The Dead-Fob Procedure Every Sierra Owner Should Know

This takes two minutes to learn and it is the difference between a minor annoyance and a service call. Do it now, in your driveway, while everything works.

Getting into the truck. There is a mechanical blade inside your fob. On most Sierras a small release lets it slide out, and there is a keyhole on the driver's door — sometimes behind a small cover on the handle. Practice removing the blade and unlocking the door once so you are not learning it in the dark at a boat ramp.

Starting the truck. Push-button GM vehicles include a backup authentication path for a dead fob battery. Your owner's manual specifies the exact method for your model year — commonly holding the fob at or against the start button, or placing it in a designated location, then pressing the brake and the button. Read that page once and note where it is.

Carrying a spare cell. A CR-type coin cell costs a couple of dollars and fits in a console. Fob batteries fail gradually, and shrinking remote range is your warning shot. If range has been getting worse, replace the cell before you assume the fob is dying.

What this does not solve. A fob that has been lost, crushed, or soaked is gone regardless of how well you know the backup procedure. The backup buys you a drive home; a second programmed fob is what actually removes the risk.

If any of the above does not work when you test it, tell us when you book — a blade that will not turn in the door lock, or a backup start that fails with a fresh battery, is worth diagnosing before the day you need it.

Common Sierra Fob Problems We See

Fob works intermittently, worse in cold or after a wash

Usually a weak fob battery or moisture intrusion. Cheap to test, cheap to fix, and worth ruling out before anyone talks about programming.

Passive entry stopped working but the buttons still work

Two different functions. The buttons are active RF; passive entry depends on the truck detecting the fob's proximity. When buttons work and passive entry does not, the fob is transmitting and the issue is usually the passive side — battery voltage is a common culprit.

Truck will not detect the fob inside the cabin

Cell phones, wireless chargers, and aftermarket electronics can interfere. Try the backup start procedure in your owner's manual — most push-button GM trucks let you hold the fob against or near the start button to authenticate. If that works, the fob is fine and the issue is detection.

One fob works, the other does nothing at all

If it is not the battery, the second fob may have been unpaired — which happens when someone runs a relearn that clears existing fobs. Repairing that is straightforward when at least one fob still works.

Owner has three fobs from three different sources and none are reliable

Aftermarket fobs vary enormously in quality. A cheap online fob that will not hold a pairing is not a programming failure, it is a parts failure.

The Honest Boundary

Two things we will not promise over the phone. First, the very newest Sierra builds with the most restricted security gateways need a VIN check before we commit to a spare-key price — access rules change by model year and we would rather tell you that now than in your driveway. Second, if your truck is genuinely all-keys-lost rather than spare-key, do not let any shop quote you the spare price. Those are different jobs with different tooling requirements, and a quote that ignores the difference is a quote that will change on arrival.

Related Services

Sierra owners in Hood County commonly pair this with other work on the same visit, which is cheaper than separate trips:

• Key fob replacement in Granbury for damaged or non-functioning fobs
• Car key programming in Granbury across all makes
• Ignition repair for older Sierras with key-slot columns
• Chevrolet key replacement for the Silverado side of the same platform
• Granbury smart key programming: dealer vs mobile for the full cost comparison
• If you are already stranded, emergency car key replacement in Granbury

Frequently Asked Questions

How much is a spare key for a GMC Sierra Denali in Granbury? As of July 2026, a spare proximity fob programmed on site in Hood County typically runs $150–$350 depending on the fob required. Lower-trim Sierras with bladed transponder keys are less. We quote the exact figure by VIN before dispatch.

Do I have to bring my Sierra to a GMC dealer for a spare fob? No. Spare fob programming on push-button Sierras is routine mobile work. There is no GMC dealer in Granbury, so the dealer route also means driving out of the county and waiting on a service appointment — mobile service typically runs 40–60% less and comes to your truck.

How long does it take to program a spare Sierra fob? Usually 30 to 60 minutes on site, including cutting the emergency blade and testing passive entry, remote start, and the dead-battery backup procedure.

How many fobs can my Sierra have paired at once? Most GM trucks support a limited number of paired fobs. If you have accumulated several over the years, some may need to be cleared before a new one is added. We check the current count before programming.

Is the emergency blade inside the fob really necessary? Yes. It is the only way into the truck when the fob battery dies at a boat ramp or a pasture gate. A spare fob whose blade was never cut to your truck is only half a spare.

My AT4's fob got wet at the lake. Can it be dried out? Sometimes, if it comes out of the water fast and the battery is pulled immediately. Often not — lake water and circuit boards do not coexist well. Either way, this is the reason to already have a second fob rather than to gamble on drying the only one.

Can you make a spare if I have already lost both keys? Yes, but it is a different and more involved job than a spare. All-keys-lost on a proximity Sierra requires diagnostic access to add the first fob back to the system, and the truck stays parked until it is done. Tell us honestly which situation you are in.

Book the Cheap Version Now

If your Sierra Denali or AT4 has exactly one working fob, that is the moment to fix it. Call or text (817) 214-2934 with your VIN and trim, and we will schedule a spare at your home, shop, or job site. Serving Granbury, Acton, DeCordova, Pecan Plantation, Tolar, Lipan, Cresson, Glen Rose, and 25 miles out. Weekdays 8:00 AM to 7:00 PM, Saturdays 8:00 AM to 5:00 PM. Or request a quote here.

Sources

• National Automotive Service Task Force — Vehicle Security Professional Program
• Texas Department of Public Safety — Private Security Program
• Associated Locksmiths of America
• National Highway Traffic Safety Administration — Vehicle Theft Prevention
• Federal Trade Commission — How to Find a Good Auto Repair Shop