Short answer: Most fob damage stops at the case. A shell swap moves the circuit board and starting chip into a new case with a freshly cut blade, so the car still knows the key. A soaked fob needs its battery out, salt rinsed off, a full dry and a new cell. A dead board means a new key, from $165.
The fob hit the parking garage floor, the dog chewed it, or it rode through a wash cycle in a jeans pocket. In many of those cases the two parts your car knows, the circuit board and the starting chip, can be saved.
Below: what a key fob shell replacement keeps and what it renews, why a car cranks without starting after a key head cracks, how to treat a fob that went in the ocean or the washer, and when a new key is the honest answer. A fob that went quiet with no damage belongs on key fob not working instead.
Car key broke off the fob or broke in half: what a shell swap does
Most remote head keys and many smart keys are a plastic case built around a circuit board, a starting chip and, on keys with a blade, a metal blank. A cracked case, a snapped blade, a torn key ring loop and button pads worn through are all damage to the case. The parts the car checks usually come through intact.
In a shell swap, the board and the chip move into a new case, and a fresh blade is cut to match your old one, or to the key code if the old blade is worn or lost. The car already knows those paired parts, so the repaired key acts like your original without the crack. Dealers generally sell a complete new key instead, which then needs pairing to the car.
Cranks but won't start after the key broke: find the chip
In many key heads the starting chip is a separate part, not something built into the board. When the head cracks, the chip can fall out; locksmith forum posts describe exactly this on Accord, Civic and Corolla keys. The remote still locks the doors and the blade still turns the ignition, but the immobilizer finds no chip, so the engine cranks without starting.
Before the broken pieces go in the trash, check the pocket, the floor mat, the cup holder and the spot where the key landed. The chip is small and easy to overlook. Found, it goes into the new shell beside the board, and the key should start the car again with nothing new to program.
If the chip is gone, a fresh one must be enrolled in the immobilizer: ordinary spare-key work when a second key still runs the car, and priced as all keys lost, $60 over the spare price, when it does not. Do-it-yourself shell swaps often leave the chip in the old case, which produces the same crank with no start.
Key fob got wet or went through the washing machine
Pull the battery out as soon as you can. If the fob went in the ocean, rinse the salt off the case and the board with fresh water. Then let every part dry fully with the case open, and fit a new cell rather than the soaked one.
Then test in order: lock and unlock from beside the car, then try to start it. If both work, the fob recovered. If the key fob got wet and won't start the car though the buttons work, the board may be damaged, and a replacement is next. Buttons that stay silent on a fresh cell point to the board too.
Some fobs come back after a soaking and some do not, and nobody can say in advance which. The steps cost only a coin cell, and the cell list by make shows which one to buy.
When the fob is past saving
A board that is cracked, corroded or still dead after drying will not work in any new case. Then a whole new key makes sense. A remote head key comes in at $165 to $259 here, where dealers quote $300 to $450, and push-button cars need a smart key: our range is $229 to $399 against a dealer's $400 to $750. Both are cut and paired at your curb.
When the dead fob was your only key, the visit is billed as all keys lost, which adds $60, and the new blade is cut to the code your VIN carries. Keep the dead fob anyway; the markings on its case and board help match the replacement.
What owners have been quoted for a broken fob
Quotes for the same damage swing widely. A 2013 Corolla owner whose key had only a broken shell was quoted $400 with tax by San Jose locksmiths, then paid $350 cash for an aftermarket key (Reddit, r/Locksmith, May 2026). In the thread, one locksmith said he charges $250, one offered $300, and one put a shell at about $30. No figure in this section is a local quote.
Dealers generally quote a complete new key. One owner reported a $740 dealer quote for a 2017 Honda Accord Touring Hybrid fob that got wet (Reddit, r/MechanicAdvice, August 2022). Another was quoted $260 at a dealer for a 2010 Corolla fob chewed by a dog (Reddit, r/Cartalk, December 2022).
Shell swaps have no fixed price on this site, because the shell, the blade and whether the chip is still in hand differ from key to key. Text pictures of each face of the fob and every broken piece, name the car's year and model, and the figure comes back on a call before anyone heads your way. Payment waits until the key starts the car.
If the blade snapped off inside a lock
A blade that broke while it sat in an ignition cylinder or a door is two jobs: the tip comes out first, then the key gets a new blade in a new shell. Extraction is $89 to $149, and the lock is not drilled. The head still in your hand holds the board and the chip, so set it somewhere safe rather than tossing it.