Bad Connector Tube

• Older oil sending units contain connector tubes which attach the output side of the oil pump to the gauge output. A worn or loose tube can result in lack of proper signals to the gauge, and should be tightened or replaced as needed.
  
  

Transducer Failure

• Some oil sending units contain a transducer which connects to a switch, which connects via a wire to the oil pressure light or gauge on the instrument panel. Transducer failure can occur due to excess voltage, and typically necessitates replacement of the oil sending unit.
  
  

Bad Switch

• The oil sending unit relies on a switch to open electrical contacts based on the level of oil pressure. This enables electricity to flow through the wire to the oil pressure gauge or light. A defective, worn or burned out switch may fail to open the contacts, resulting in incorrect oil pressure level readings to the computer.