Computer/sensor problems

I bought a 2009 Ford Explorer in decent condition
for its age and mileage (over 100,000). Had it
serviced and it runs pretty well except for a
constant minute long alarm that goes off every 15
minutes or so when I’m driving it, alerting me that
the brake fluid is low, when it isn’t. It will also alert
me of other problems but usually when I get the
problem fixed it stops alerting me to that one. The
brake fluid warning beeping is something that has
never stopped. Another example is one of the tires
was leaking air and it began alerting me of low tire
pressure, well I changed the tire and the warnings
continued, until the lights began flashing and it
read “tire sensor fault” or something like that, just
wondering if it’s a fixable problem because
obviously it’s a computer issue.