KEYBattery and contacts
Check the battery type and polarity against the key manufacturer's guidance. Inspect the holder for loose connections, contamination and damaged solder joints.
Car key repair starts with a closer look.
Understand a key fob fault, identify its circuit board, and inspect the components that matter.
Explore the free interactive PCB demo →Why has a car key stopped working?
A damaged case, worn button, poor battery contact, cracked solder joint or water damage can all affect a key fob. Similar symptoms can also come from the vehicle, pairing or immobilizer system. The first step is to describe exactly what stopped working: remote locking, proximity detection, starting, or one particular button.
Ask when the fault started and whether the key was dropped, got wet, had its battery changed or was repaired before. If an available spare works, that is a useful clue, but it does not identify the failed component by itself.
What to inspect before fixing a key fob
Buttons and case
Look for broken case supports, missing switch caps and damaged tactile switches. A worn case can stop a good switch from being pressed correctly.
The circuit board
With power removed, inspect both PCB faces under magnification. Look for cracks, lifted pads, missing components and corrosion. Match the board revision and identifiers before choosing a reference.
Key PCB components, explained
Resistors limit current or form part of sensing circuits. Capacitors store charge and help with filtering. Inductors and coils serve different functions in power and radio circuits. Integrated circuits handle the key's control and radio functions. A component's appearance alone does not establish its value or whether it is faulty.
Measurements depend on the part, circuit and test conditions. A continuity beep alone is not a complete component test, and in-circuit readings can include parallel paths. Use a matching reference and appropriate equipment before replacing parts.
Water damage and corrosion
Remove the battery before inspecting a wet key. Corrosion may affect contacts, component leads, vias and tracks on either side of the PCB. A repaired track must follow a verified connection; guessing a bridge can create a short or damage another component.
Repairing PCB damage and programming a key are different jobs. A physical repair does not necessarily restore pairing or resolve an immobilizer fault. Vehicle-specific procedures may still be needed.
Explore the interactive car key database
KeyLab combines front and back PCB views, clickable component locations, recorded chip markings and frequencies. Search by manufacturer or identifier, compare the board with the key in front of you, and use the included Repair Basics to build your inspection skills.
The library is a technical reference for key repair professionals. Enhanced illustrations help with inspection; recorded identifiers and the original physical board take priority over illustrative lettering. Exact vehicle compatibility is not established by a similar-looking PCB.