Possible cause
WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.
- Instrument cluster malfunction
- Rear body control module (RBCM) malfunction
- Fuel gauge sender unit malfunction
- Open or short circuit in wiring harness between fuel gauge sensor unit and rear body control module (RBCM)