23-02-17, 10:28 PM
There are many, many possible causes.
It could be a failing component somewhere or it could be an intermittent open circuit or (less likely) intermittent short circuit in the wiring. You might be able to narrow down the search if there are any other unexplained faults, such as flickering lights or intermittent glitches on the instrument panel for example.
Sadly vehicle wiring problems are a pain in the arse… and they're a hundred times worse if they only show up when they feel like it (i.e. when you're late for work or at midnight on your way home).