New Holland ENG 496 – ENG (Engine Controller / Engine ECU): Engine Speed / Position Sensor #2 supply is too low

This fault code indicates that the 5-volt DC reference supply voltage going to the #2 Engine Speed / Position Sensor has dropped below the acceptable operating threshold. When the voltage is pulled low, it typically points to a short-to-ground in the wiring harness, an internal short within the sensor itself pulling the reference voltage down, or a failure within the ECM's power supply circuit.

• New Holland CR8.90 Revelation Combines
• New Holland T8040 Tractors
• Machines utilizing the 8.3L, 9.0L, 12.9L, and 15.0L engine platforms

1. 1

   Isolate the Sensor vs. Wiring: Disconnect the Engine Speed / Position Sensor #2. Turn the key to the ON position (engine OFF) and use a multimeter to measure the voltage at the supply pin on the harness connector. It should read approximately 5 VDC.

2. 2

   Test for an Internally Shorted Sensor: If the 5V supply is present when the sensor is unplugged but drops significantly when the sensor is plugged back in, the sensor is internally shorted and must be replaced.

3. 3

   Inspect the Wiring Harness: If the voltage is low or zero while the sensor is unplugged, trace the wiring harness back to the Engine ECU. Look for chafing, pinched wires, or melted insulation causing the supply wire to short to ground or to another circuit.

4. 4

   Check ECU Output: If the wiring harness tests good (no shorts to ground and continuity is intact) but there is still no 5V supply at the connector, test the output directly at the Engine ECU pin. If the ECU is not outputting 5V, the controller itself may be faulty.

1. 1

   Disconnect battery

   Turn off the machine and disconnect the battery to prevent electrical arcing or ECU damage during repair.

2. 2

   Locate sensor

   Locate the Engine Speed / Position Sensor #2. (Note: Depending on the specific engine displacement, Sensor #1 and #2 correspond to the Camshaft and Crankshaft position sensors. For example, on 15L engines, the Cam sensor acts as the speed sensor, while the Crank acts as the position sensor).

3. 3

   Repair or replace wiring harness

   If the harness is damaged: Repair the shorted section of the wiring harness using proper OEM-approved splicing techniques and heat-shrink tubing, or replace the affected harness section.

4. 4

   Remove faulty sensor

   If the sensor is faulty: Remove the retaining bolt securing the sensor to the engine block or timing gear housing. Pull the old sensor out.

5. 5

   Install new sensor

   Clean the mounting surface. Install the new Engine Speed / Position Sensor. (Note: Ensure proper seating; some older CNH engine sensors require specific shimming, though most modern ones are fixed-depth).

6. 6

   Reconnect harness

   Reconnect the sensor harness securely.

7. 7

   Clear fault codes

   Reconnect the battery, turn the key to the ON position, and clear the inactive fault codes using an electronic service tool (e.g., New Holland Electronic Service Tool) or the in-cab display.

8. 8

   Verify repair

   Start the engine and verify that the ENG 496 code does not return and that the engine RPM reads correctly without stalling or derating.