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A Fob That Stopped Locking the Doors Usually Just Needs a Battery

Most of the time, a fob that quit locking the doors needs a fresh coin cell, and that is what you hear when you call. Fitted at your car, it is $20 to $45.

Call about a fob that quit locking the doors and the first answer is usually the cell it takes and where to buy one. In our experience it is the battery nine times out of ten, and hearing that on the phone costs you nothing.

We ask whether the engine still starts on that key, whether the range shrank for a few weeks before the buttons quit, and when the cell was last changed. Yes, yes and never add up to a battery. The fob battery guide by make lists the usual cell for your car.

A visit makes sense when there is no time for a parts store, when the case is tight and you would rather not crack it, or when we are at the car for another job anyway. A dealer fits the same cell for $15 to $30, once you have driven in and waited.

A smart key being paired at the car.

Key fob battery prices

Every key fob battery price below includes the drive to you anywhere in the county. The dealer column is what a San Diego dealership typically charges for the same job.

Prices as of 2026-09-30. Your exact price is confirmed on the phone before we drive.
Key or jobTypical dealerValue Car KeysYou keep
Key fob battery, fitted at your carNearer $20 alongside another job at the car; nearer $45 when the battery is the only reason we come out. $15 to $30 plus the visit $20 to $45 see note
Pair a fob that still will not answer after a new cellFor a fob the car no longer lists: your original, or one that is new and never paired elsewhere. $120 to $200 $79 to $119 $41 to $81
Remote head key, when the circuit is damagedA snapped clip or a flooded board usually means a new key, cut and paired at the car. $300 to $450 $165 to $259 $135 to $191
Smart key, when the fob itself has failedOrdered to your car's part number, then enrolled for entry and push-button starting. $400 to $750 $229 to $399 $171 to $351

How the visit goes

  1. Call or text before buying anything

    Give us the car and what the fob is doing. If it points at the cell, you get the cell number and a choice: a parts-store cell for a few dollars, or $20 to $45 with us fitting it.

  2. Open it, swap it, match the orientation

    Most cases separate at a seam or notch, as described in the owner's manual, and many smart keys open once the emergency blade slides out. Note which face of the old cell points up and seat the new one the same way.

  3. Step back and press every button

    Lock, unlock and trunk from a few car lengths away. When they answer, the job is done. If they stay silent, we check the fob on the spot and price pairing or a replacement before starting either.

Battery or something else: the quick sort

A cell fades rather than failing in one step. Range that shrinks over weeks, a button that wants a second press, and a low-battery warning in the instrument cluster all point to it. A fob that died the day it went in a pool, one button that quits while its neighbors work, or buttons still dead after a new cell point somewhere else.

Reading the number on the cell

Coin cells are named by size. In CR2032, the 20 is the diameter in millimeters and the 32 is the thickness in tenths of a millimeter, so a CR2016 is the same width at half the thickness. Buy the size marked on the cell you took out, not whichever one drops into the slot, because a thinner cell can rattle loose and lose contact when the fob is bumped.

When a fresh cell changes nothing

Then the pairing or the fob is at fault. A fob whose rolling code slipped out of step can sometimes be brought back with the resync steps in your manual. One the car no longer lists needs fob programming: $79 to $119 with us, $120 to $200 from a dealer.

A snapped battery clip, a cracked solder joint at the cell holder, or green corrosion after a wash means the board is finished. That calls for a new key: a remote head key from $165, or a push-to-start smart key from $229.

Known problems by make

When the fault is a known one on a particular make, the page for it has the years, the fix and both prices.

Nissan steering lock no-start

Push-button Altimas of 2007 to 2012, 2009 to 2012 Maximas, the 370Z, Cube, G35 and G37 can refuse to start when the electronic steering lock fails.

Mazda keyless system malfunction

On push-button Mazdas, from the CX-5 and Mazda3 to the MX-5, a Keyless System Malfunction warning often starts with an added used or aftermarket fob.

Car key problems by make, and what each dash message means

Questions people ask

What does a key fob battery replacement cost?

$20 to $45 when we fit it at your car, drive included, with the low end applying when we are already there for another job. A dealer charges $15 to $30, after you drive in and wait. The bare cell costs a few dollars over a parts-store counter, and we will name it on the phone.

How can I tell whether the battery is the problem?

When the engine keeps starting on that key while its buttons fade, suspect the cell first; the chip in a turn-key car draws nothing from it. Range that shrank over a few weeks and a battery warning on the dash point the same way. A fob that stopped the day it got wet points to the fob instead.

Does the car forget the fob while the battery is out?

Not on most cars. The car keeps its own list of fobs, and the fob stores its pairing in memory that holds without power, so a swap lasting a minute or two changes nothing. A few fobs lose sync and need the manual's resync steps; if that fails, pairing is $79 to $119.

Can a dead fob battery lock me out of my car?

It leaves the buttons dead, but nearly every fob either is a key or hides one. Slide the release on a smart key and a metal blade slides free to work the driver door lock, sometimes hidden under a cap on the handle. If that blade has gone missing too, a lockout visit is $79 to $129 and leaves the door unmarked.

What size cell does my fob need?

Whatever size is marked on the cell already in it. Common ones are CR2032, CR2025, CR2016, CR1620 and CR1616, and some larger fobs take a CR2450. The fob battery guide lists the usual cell by make and key style, or call with the car's details and we will name it.

Prices by make

The makes that call about key fob battery most often. Each make page lists its key types by model year.

Toyota keys

from $129 at your car
Keep up to $251 vs the dealer

Honda keys

from $139 at your car
Keep up to $241 vs the dealer

Ford keys

from $129 at your car
Keep up to $211 vs the dealer

Nissan keys

from $135 at your car
Keep up to $271 vs the dealer

Hyundai keys

from $129 at your car
Keep up to $231 vs the dealer

Every make we cover

Guides

Get the dealer's key without the dealer's bill

Call or text (619) 340-1518 with the car's year, make and model. If a dealer already quoted you, send that quote over for our answer on the same key.

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