New Holland 13031 – INST: Hydraulic Oil Temp Sensor Voltage Low

The INST (Instrumentation) control module has detected that the signal voltage from the hydraulic oil temperature sensor is significantly lower than the minimum expected value. This indicates a short circuit to ground, which is typically caused by the sensor's signal wire coming into electrical contact with the machine's chassis or another ground path, or by an internal failure within the sensor itself.

• T7
• T8
• L-Series
• C-Series
• Combine Harvesters
• Sprayers
• L213
• L215
• L218
• L220
• L221
• L228
• L230
• TX66

1. 1

   Visually inspect the wiring harness leading to the hydraulic oil temperature sensor for chafed insulation, pinched wires, or areas rubbing against the frame or hydraulic components

2. 2

   Check the electrical connectors at the sensor and the INST controller for corrosion, dirt, moisture, and ensure they are securely fastened

3. 3

   With the key off, disconnect the sensor and use a multimeter to check for a short to ground on the signal wire terminal in the harness (should read open circuit/infinite resistance)

4. 4

   Measure resistance across the disconnected sensor's terminals; a reading of very low or zero ohms indicates an internal short in the sensor

5. 5

   Test the sensor by placing it in hydraulic fluid of a known temperature, heating it, and observing if the resistance changes appropriately (no change indicates a failed sensor)

1. 1

   Prepare machine for service

   Park the machine on a level surface, lower all attachments to the ground, turn off the engine, engage the parking brake, and allow the hydraulic oil to cool.

2. 2

   Locate and disconnect sensor

   Identify the hydraulic oil temperature sensor (typically in the hydraulic reservoir, on a filter housing, or near the hydraulic pump) and disconnect its electrical harness connector.

3. 3

   Diagnose the fault

   Perform the diagnostic checks listed above to determine if the fault lies in the wiring or the sensor itself.

4. 4

   Repair wiring harness

   If a short to ground was found during testing, carefully repair the damaged section of wire. Ensure the repair is insulated and re-route the harness away from rubbing components.

5. 5

   Replace temperature sensor

   If the sensor failed resistance testing, unscrew it from the tank or filter base (be prepared to catch leaking fluid). Install the new sensor with correct sealing washers/O-rings, torque to manufacturer specifications, and reconnect the harness.

6. 6

   Clear codes and verify

   Turn the ignition on, clear the fault codes using the machine's diagnostic menu or a service tool, start the machine, and operate the hydraulic systems to operating temperature to verify code 13031 does not return.