P0940: Hydraulic Oil Temperature Sensor Circuit High Input

MediumPowertrainEngine Oil System

What does P0940 mean?

P0940 is a diagnostic trouble code indicating "Hydraulic Oil Temperature Sensor Circuit High Input". The ECU is reading a voltage that is above the expected range. This can be caused by a short to power in the wiring, a failed sensor, or a connector issue in the engine oil system.

Symptoms you may notice

  • Check engine light (MIL) illuminated on dashboard
  • Engine overheating
  • Temperature gauge reading high
  • Heater not working properly
  • Intermittent warning lights

Common causes

  • Damaged or corroded wiring harness
  • Loose or disconnected electrical connector
  • Failed engine oil system sensor or actuator
  • Blown fuse in the related circuit
  • Poor ground connection

What should you do?

Schedule a diagnostic appointment at your earliest convenience. The vehicle is generally safe to drive short distances, but the underlying issue should be addressed to prevent it from worsening.

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