New Holland ENG 3794 – Engine Control Unit (Engine ECU): Intake Air Pressure Sensor: Plausibility Check for air pressure at the upstream of intake valve sensor

The Engine Control Unit (ECU) is receiving a signal from the intake air pressure sensor (commonly known as the boost pressure sensor or MAP sensor) that does not make logical sense when compared to other engine operating parameters (such as engine speed, throttle position, or atmospheric pressure). The sensor may be outputting a voltage that is either too high or too low for the current engine load.

• T6.120
• T6.140
• T6.150
• T6.160
• T6.175
• T7.170
• T7.185
• T7.200
• T7.210
• TS110A
• TS125A
• TS135A
• CR9090
• CX8080
• CX8090
• L-Series
• C-Series
• SR/SV models

1. 1

   Inspect the sensor's wiring harness and 4-pin connector for damage, corrosion, or loose connections

2. 2

   Using a multimeter, check the output voltage of the intake air pressure sensor to see if the signal is stuck too low or too high

3. 3

   Connect a mechanical manometer (pressure gauge) to the intake manifold to verify the actual physical boost pressure and compare it to the sensor's electrical output

4. 4

   Inspect the intake manifold, intercooler, and turbocharger hoses for physical leaks, blockages, or disconnected lines

1. 1

   Turn off machine and disconnect battery

   Turn off the machine and disconnect the battery to prevent electrical shorts or accidental ECU damage.

2. 2

   Locate sensor

   Locate the Intake Air Pressure Sensor (Boost Pressure Sensor) on the engine's intake manifold.

3. 3

   Disconnect harness

   Depress the locking tab and disconnect the electrical harness connector from the sensor.

4. 4

   Remove retaining bolt

   Remove the retaining bolt(s) securing the sensor to the manifold.

5. 5

   Remove sensor

   Carefully pull the sensor out of the manifold.

6. 6

   Clean mounting surface

   Clean the mounting surface on the intake manifold, ensuring no dirt or debris falls into the engine intake.

7. 7

   Install new sensor

   Install the new sensor (ensure the O-ring is properly seated) and tighten the retaining bolt.

8. 8

   Reconnect harness

   Reconnect the electrical harness connector until it clicks into place.

9. 9

   Reconnect battery

   Reconnect the battery.

10. 10

    Clear fault code

    Use a diagnostic tool (such as the CNH Electronic Service Tool) to clear the ENG 3794 fault code from the Engine ECU memory.

11. 11

    Verify repair

    Start the engine and operate it under load to verify the fault code does not return.