Key Fob Not Working? Battery or Programming

A fob that stops responding is usually a small problem. Before you call anyone, work down this list in order. Most of it takes a few minutes and no tools.

Step 1: The battery

A flat battery is the most common cause by a wide margin. Most fobs use a CR2032 or CR2025 coin cell. Some use a CR2016 or CR1620. The number is printed on the old battery, so match it exactly.

Signs it is the battery:

• Range has been shrinking for weeks.
• You have to press the button twice, or stand next to the door.
• The dash shows a low key battery warning.

To change it, look for a small notch on the seam of the fob. Open it gently with a coin or a flat screwdriver. Note which side of the battery faces up before you lift it out. Drop the new one in the same way and snap the case closed. Pharmacies along Orange Avenue and most grocery stores carry these cells.

Step 2: Try the second fob

If the spare works, the car is fine and the problem is the first fob. Battery, worn buttons, or lost sync are the usual suspects.

If neither fob works, look at the car instead. A weak car battery, a blown fuse, or a receiver fault will stop every fob at once. New batteries in both fobs will not fix that.

Step 3: Distance and interference

Walk closer. Underground garages, steel-framed buildings, and places with heavy radio traffic can cut a fob’s range. If the fob works up close but not from across the lot, it may be a weak battery again, or simply the spot you are in.

Step 4: Use the hidden key

Almost every fob hides a mechanical key inside. Slide the small latch on the back and pull the blade out. On many cars the driver’s door lock sits under a plastic cap on the handle. Look for a slot on the underside of the cap and lift it off with the blade.

Opening the door this way may set off the alarm on some cars. It stops once the car starts with the fob, or once you get the fob to work as described below.

Step 5: The fob-to-start trick

Push-button cars have a backup for a dead fob. Depending on the model, you either hold the fob directly against the start button and press, or set it in a marked slot in the center console, the cup holder, or a pocket near the steering column. The owner’s manual shows the spot. A quick search for your model and “key fob dead” also finds it.

If the car starts this way, good news. The chip that talks to the immobilizer is fine. Only the remote side of the fob is weak, which almost always means the battery.

Reprogram or replace?

Signs the fob needs reprogramming

• The battery is new, the spare works, and this fob does nothing.
• The fob stopped working after the car sat for a long time with a dead battery. Some cars lose sync with the remote.
• The remote buttons work but the car refuses to start with it. The transponder side needs a look.

Signs the fob needs replacing

• The case is cracked or the buttons are worn through.
• It went in the bay, the ocean or the washing machine.
• It rattles after a drop, or the board shows green or white corrosion.
• Reprogramming was tried and failed.

We test the fob at the car and tell you which it is. If it needs a replacement, we supply, cut and program one on site. See key fob programming.

A note on buying a fob online. Check the exact part number on your old fob. Some brands lock a fob to the first car it is programmed to, so a used fob may never work on yours.

Salt water and sand

Beach towns are hard on fobs. Coronado, Ocean Beach, Pacific Beach and Mission Bay all see the same failures.

• Salt water conducts and corrodes. If the fob gets wet, pull the battery out right away. If it was salt water, rinse the board gently with fresh water. Let it dry for a full day in a warm, dry place. No hair dryers and no ovens.
• Sand gets under the buttons and stops them clicking. A soft brush and a puff of air help. Do not pick at the rubber.
• The best fix is prevention. Keep the fob in a dry bag at Central Beach or on the boardwalk near Crystal Pier, or leave it with someone on the sand. Damp pockets shorten a fob’s life more than anything else.

If you have worked through the list and the fob still will not cooperate, call or text (619) 313-6749. We come to the car wherever you are in Coronado or San Diego, across our service area, any day from 7:30 AM to 10:30 PM, and give you the price before we start.