Key Problem: Ford Focus 2006
I have a 2006 Ford Focus. I installed a new car stereo two months ago. Afterwards, I tried to open the car using my key as I usually do and it would not open. I have the standard edition and there is only one locking door to enter and exit the car. Thus, I was locked out of the car. I figured out that I could climb through my trunk and was able to unlock the car that way. I tinkered with it for awhile and I turned off the car and disconnected the negative from the battery terminal. I turned the ignition switch twice and then put the negative back on the battery again. I turned the car on and locked the door. I was able to unlock and lock the door for two months. Today the same problem started again. I tried the same solution that had worked last time twice and it did not work either time. What is wrong with my car and lock? How do I fix it?