Why a wet fob is a common South Florida problem
Life here involves water. People swim in pools, wade in the ocean, launch boats, wash cars and get caught in sudden downpours that soak a pocket before they reach shelter. A key fob that travels in swim trunks, a beach bag or a back pocket is exposed to water more often than the people who designed it might have hoped.
Modern key fobs are small electronic devices. Inside the plastic case there is a circuit board, a small radio transmitter, buttons and a battery. Some fobs are sealed against splashes, but few are designed to be submerged. Many are rated, if they are rated at all, for light rain rather than a swim.
The result is that water damage to fobs is one of the most common reasons for a call about vehicle keys here. Sometimes the fob fails right away. More often it behaves strangely for a few days, and then fails when the corrosion has had time to work. By the time it stops, the person has often forgotten what happened.
This page explains what to do and what to expect. It does not describe any method for defeating a vehicle's security. A technician will ask for proof of ownership before making or programming any key.
What to do in the first minutes
The faster you act, the better the chance of saving the fob. First, take it out of the water. Do not press any buttons. Pressing buttons while the fob is wet can draw power through the moisture and short the circuit. If the fob has a removable battery, and you know how to open it, take the battery out as soon as you can. A battery that stays in a wet fob can speed corrosion and may leak.
Next, shake off the excess water and open the case if it is designed to be opened. Many fobs have a small slot where a coin or a thin tool lifts the shell apart. If you are not sure how to open yours, look it up or skip this step, since forcing the case can crack it. If you can open it, lay the pieces on a clean towel or a paper towel with the circuit board facing up.
Let the fob dry slowly in a dry, room-temperature place for a day or two. Do not use a hair dryer, an oven, a microwave or a heater, since heat can warp the plastic and damage components. Do not shake or tap it repeatedly. If it was in salt water, a gentle rinse in clean, fresh water before drying can help wash away salt, but only if you can then dry it thoroughly.
Avoid putting the fob in a bag of rice. This is a popular suggestion, but it does not remove moisture well, and small grains can get inside the case.
- Take the fob out of the water and do not press any buttons
- Remove the battery if you can do so safely
- Open the case if it is designed to open, and lay the parts out to dry
- Let it dry slowly at room temperature for a day or two
- Do not use heat, and skip the rice
What water and salt actually do inside the case
Fresh water is a problem, but salt water is a bigger one. Water itself can connect parts of the circuit that should not be connected, creating a short that stops the fob from working. Even after the water dries, minerals and salt are left behind. Salt is conductive, and in humid air it attracts moisture, so a fob with salt residue can continue to misbehave long after it looks dry.
Corrosion is the slow damage. Metal contacts, battery terminals and solder joints can oxidize. A green or white crust on the contacts is a sign of corrosion. The buttons may begin to respond weakly or intermittently. The range may shrink so that the fob only works when you are right next to the car. The indicator light may flicker.
Battery leakage can compound the problem. A battery that has been wet may leak, and the leaked material can eat into the circuit board. If you see residue around the battery, the fob may be beyond simple repair.
Sometimes a fob that dried well works perfectly again. Sometimes it works for a while and then fails. Because the damage can be hidden, a fob that has been submerged should not be fully trusted afterward. Our page on key fob battery and replacement describes how batteries and fobs wear in ordinary use.
Signs a fob is failing after getting wet
Learn to recognize the signs of a fob that is on its way out. The most common is reduced range: you used to unlock the car from across the lot and now you must be a few feet away. Another is inconsistent response: you press the button, nothing happens and then it works on the third try. A third is a dead or flickering indicator light. A fourth is a smart key that no longer lets the car recognize it, so the car will not start or displays a message about the key.
Other signs include sticky or unresponsive buttons, a case that feels warm, a rattling sound inside or visible moisture under the plastic. A rattle can mean that a part has come loose or that the case has filled with a small amount of water.
If you notice any of these after a soaking, act on them. Do not wait for the fob to fail completely. A fob that works intermittently is more likely to fail at an inconvenient time, such as when you are far from home or when you have no spare.
If the fob stops working while the car is locked and you are outside it, the vehicle may still be accessible with a physical key hidden in the fob. Many fobs contain a small mechanical key for this purpose. Our page on smart key and push-button start problems explains how these systems work.
The backup key and what it can and cannot do
Most modern fobs have a hidden mechanical key, a small metal blade that slides out of the case. It is there so that you can unlock the driver's door if the fob battery is dead or the fob has failed. It does not start the car. Starting a push-button car with a dead or unrecognized fob usually involves holding the fob against a specific spot on the dashboard or steering column so that the car can read a chip inside the fob, even without battery power.
If your fob has been soaked, the chip may still work even if the buttons do not, since the passive chip does not rely on the battery. This is why a fob that seems dead sometimes still lets the car start when held against the right spot. The owner's manual for your vehicle will show where to hold it and how.
If neither the backup key nor the chip works, the fob may be beyond use, and a replacement will be needed. Replacement involves obtaining a new fob that is compatible with your vehicle, cutting the backup key if applicable and programming the fob so that the car recognizes it. For many vehicles, this requires dedicated equipment and information about the car.
Do not try to open the car with improvised tools if the key fails, since doing so can damage the weatherstripping, the door and the paint. Call instead.
When a replacement fob is the realistic path
If a fob has been submerged in salt water, shows corrosion, has stopped responding or has become unreliable, replacement is often the practical choice. Repair is rarely an option for a modern fob, because the circuit board and chip are not designed to be serviced.
A replacement fob must match your vehicle's make, model and year, and often the specific features, such as remote start or a power liftgate button. A fob that looks identical but is for a different frequency or a different chip will not work. A technician will ask for the vehicle identification number, the year, make and model and proof of ownership before supplying a fob.
Programming is the second step. The new fob must be introduced to the car so that the car recognizes it and, in many cases, so that the old fob is removed from the list of trusted keys. Some vehicles allow owners to program certain fobs themselves with a sequence of steps, while many require a diagnostic tool. A locksmith with the right equipment can program on-site for many vehicles.
Our pages on lost car key fob and transponder key programming explained describe what is involved in more detail. Quotes are given only by phone, and complicated or newer vehicles may need an on-site visit first.
Proof of ownership and why it matters
Before making or programming a key, a responsible locksmith confirms that the person asking owns the vehicle or has the owner's permission. The reason is simple: a key is the vehicle. A technician who makes keys for anyone who asks makes it easy for a thief.
Expect to show photo identification and the vehicle's registration or title. The name on your identification should match the name on the registration, or you should be able to show that you are authorized, such as by a lease, a rental agreement or a letter from the owner. For a company vehicle, a fleet manager or an authorized employee must confirm.
If your registration was in the glove box and the vehicle is locked, that is a common problem. A registration copy in your phone or in your wallet helps. Some people photograph the registration and insurance card and store them where they can reach them. Our page on vehicle ownership proof needed lists documents that commonly work.
If you are using a borrowed or rented vehicle, contact the owner or rental company first. They may have a spare or an approved process and may need to authorize work.
Protecting your fob from water in the first place
A little planning goes a long way. If you are heading to the beach, pool or boat, leave the fob in a secure place rather than in your pocket, if you can. Many people use a small waterproof pouch or a floating key ring. Some leave a spare in a hidden, secure place and carry only the backup mechanical key while swimming.
Silicone covers can offer a little protection from splashes and impact, but they do not make a fob waterproof. A fob in a pocket of a wet bathing suit is still at risk. If you ride a boat or a jet ski, a waterproof dry bag for keys and phones is a sensible investment.
Keep a spare fob, and keep it somewhere dry and safe, such as at home. A spare that has never been in the water is a sensible safeguard. Check it from time to time to make sure it still works and that the battery is fresh.
If you work around water, consider a physical key for the vehicle that is separate from the fob, such as a valet key. A technician can discuss options by phone. Our page on spare car key making explains how spares are made.
Rain, humidity and the slow version of water damage
Not every fob that fails has been dropped in a pool. In a climate with frequent heavy rain, high humidity and warm temperatures, moisture creeps into fobs slowly. A fob carried in a pocket against a sweaty leg, stored in a damp beach bag or left in a boat compartment can take on moisture over weeks. The case may look dry, but condensation inside can form whenever the fob moves from air conditioning to outdoor heat.
The slow version of water damage is harder to diagnose because there is no single moment to point to. The range shrinks over a few weeks. A button begins to feel stiff. The battery drains faster than it should. People often replace the battery, find the fob works for a few days and then fails again, which is a sign that the problem is not the battery at all.
If you suspect slow moisture damage, open the case if it is designed to open and look. A white or greenish crust on the battery contacts, a faint film on the circuit board or rust on small metal parts are all signs. Clean contacts gently with a dry cotton swab if you are comfortable doing so, and let the fob air out. If the problem returns, replacement is the more reliable path.
Prevention is similar to the swimming case: store the fob somewhere dry when you can, avoid leaving it in damp bags and keep a spare at home. A fob that lives in a dry drawer will outlast one that lives in a beach bag.
What to do if the car will not start or open
If the fob is wet and the car will not respond, check the simple things first. Try the backup mechanical key in the driver's door. Try the manual start procedure in your owner's manual, which usually involves holding the fob in a specific spot. Check the vehicle's battery, since a dead car battery can mimic a failed fob.
If you are locked out and the fob has failed, and the backup key is not available, do not try to force the door. Call a locksmith. A technician will ask for proof of ownership and will explain how charges work, including the service call charge. Quotes are given only by phone.
If a child or pet is locked in the vehicle, call 911 first. Do not wait for a locksmith. Heat inside a car rises fast, and the response is time-critical. See child or pet locked in a car.
When you are ready, call and describe what happened to the fob, the vehicle's make, model and year and whether the car still starts. The more specific you are, the more accurately a dispatcher can guide you.
Questions people ask
Should I put a wet key fob in rice?
No. Rice does not remove moisture well, and grains can get into the case. Take out the battery if you safely can, avoid pressing buttons, open the case if it is designed to open and let the parts dry slowly at room temperature. Do not use heat. If it still misbehaves afterward, plan for replacement.
My fob fell in the ocean. Is it ruined?
Possibly. Salt water leaves conductive residue and speeds corrosion, so even a fob that dries and works may fail later. A gentle rinse in clean water followed by thorough drying can help, but you should not fully trust it afterward. Keep a spare, and plan for replacement if it behaves oddly.
The buttons do not work, but can I still start the car?
Often yes. The passive chip in many fobs works without battery power if held against a specific spot on the dashboard or column, as shown in the owner's manual. The hidden mechanical key can open the driver's door. If neither works, the fob likely needs replacement and programming.
What proof do I need to get a replacement fob?
Photo identification and the vehicle's registration or title, with the name matching or with written authorization from the owner. A technician will also need the make, model, year and often the vehicle identification number. Rental and company vehicles need confirmation from the owner or fleet contact.
Can a water-damaged fob be repaired?
Rarely. Fob circuit boards are not designed to be serviced, and corrosion often spreads beyond what is visible. Replacement and programming is usually the realistic path. A technician can advise by phone, and newer or complicated vehicles may need an on-site visit before a firm quote is possible.
What should I do if my child or pet is locked in the car?
Call 911 immediately. Heat inside a closed car rises fast, and emergency responders are trained and equipped to respond. Do not wait for a locksmith. Once the emergency is over, a locksmith can help with any key, fob or lock problems, subject to proof of ownership.
Describe the situation by phone and we will tell you what the job involves. Quotes are given by phone. Jobs that cannot be quoted without seeing them need a technician on site, and the service call charge is explained on the phone before anyone is dispatched.