Van, Truck, Trailer, Bus and Coach Aftermarket News in Ireland

What causes an oil temperature sensor to fail? 

Through its helpful website, TechWorld (, Hella has assisted thousands of technicians with their everyday fitment queries. One of the more common enquiries is what causes an oil temperature sensor to fail and how to resolve it.

Nowadays, oil temperature sensors are fitted in the majority of vehicles and, depending on the make and model, theymay be installed in addition to an oil pressure sensor.

The function of the sensor is to let the engine know when the oil is at the right temperature for it to perform optimally, which it does by sending information to a separate instrument or to the ECU for monitoring the oil temperature in the engine. In modern vehicles, the oil temperature sensor is integrated into the oil level sensor.

Possible causes of failure can include:

  • Contact failure on connector
  • Internal short-circuits
  • Damaged measuring element

Sensor failure will result in the engine management system missing or receiving incorrect information about the engine oil temperature and therefore should be replaced as soon as possible. 

To resolve this problem, Hella recommends that technicians check the electrical connectors and wiring for damage and verify the resistance values of the sensor in order to decide whether to replace the oil temperature sensor.