As winter arrives, many drivers across the UK face the frustrating issue of their car keys failing to work. This problem usually occurs when the temperature drops below -2°C, but in some cases, it can happen even at higher temperatures.
In this article, we’ll walk you through a relatively simple method to resolve the issue of a car key not working in cold weather.
Disclaimer:
We are not directly responsible for the outcome of this method, as its success depends on the quality of your work and the specific characteristics of your car key.
Let’s look at the process using Mazda 6 keys as an example.
Key Fob Not Working When Cold: What to Do
Step 1: Disassembling the Key Fob
Press the button
Open the key
Press the lock with a thin screwdriver and…
…separate the lower part of the key
Insert the screwdriver into the groove and carefully separate the two halves of the key:
Set the parts aside if you don’t plan to replace the battery.
Step 2: Remove the Circuit Board
Take out the circuit board and detach the rubber seal:
Here is the cause of the issue
Step 3: Identifying the Problem
Here is the cause of the issue:
The signal level for the buttons is controlled by two resistors, marked with circles in the photo:
Under normal conditions, these resistors have a resistance of 1 kΩ. However, over time, parasitic resistance builds up in the buttons and circuitry (likely due to a design flaw).
- The left resistor is responsible for the lock/unlock buttons.
- The right resistor is responsible for the boot release button.
Step 4: Replacing the Resistors
To fix the issue, replace these components with equivalents of 550–700 Ω. This should restore the functionality of your key fob.
However, the soldering work is very delicate. If you don’t have a fine-tip soldering iron, a hot air soldering station, or experience with SMD (surface-mounted device) components, it’s best to leave this task to a professional car locksmith.
As an additional measure, you can ask a professional to reheat the entire circuit board.
Step 5: Replace the Battery
It’s also a good idea to replace the battery while the key is disassembled. Choose the freshest possible battery, preferably from a reputable brand like Panasonic.
Step 6: Reassemble and Test
Reassemble the key fob in reverse order, test it, and enjoy your restored key fob functionality!
Car remote not working in cold weather
If after following all the steps above the key still does not work, you can always contact us at Phoenix Car Keys. We specialise in car key replacement and are ready to diagnose or replace your car key in the shortest possible time and provide a 12-month warranty.
