New Holland ENG 122 – ENGINE Controller (Engine ECU): Boost Pressure Sensor voltage is too high.

The Engine Control Unit (ECU) is detecting a voltage signal from the Boost Pressure Sensor (also known as the MAP sensor) that exceeds the normal operating range (typically near or above 4.5V - 5.0V). This usually indicates a short to a high-voltage source (like a 5V reference or 12V battery wire) in the wiring harness, a broken/open ground circuit, or an internal short within the sensor itself.

• T6.120
• T6.140
• T6.150
• T7.170
• T7.200
• TS110A
• TS125A
• TS135A
• T8000 Series
• SR130
• SR160
• SR175
• SV185
• MX Magnum
• Magnum 215
• Magnum 245
• Magnum 275
• Magnum 305
• Magnum 335

1. 1

   Visual Inspection: Inspect the Boost Pressure Sensor, its electrical connector, and the wiring harness for visible damage, corrosion, or loose pins.

2. 2

   Voltage Drop Test (Sensor Unplugged): Disconnect the sensor and turn the key to the ON position. Use a multimeter to check the signal wire voltage. If the voltage remains high (e.g., 5V or 12V) with the sensor unplugged, there is a short to power in the wiring harness between the sensor and the Engine ECU.

3. 3

   Ground Circuit Test: Check the sensor ground circuit for continuity to the ECU ground. An open ground wire will cause the signal voltage to float high.

4. 4

   Sensor Verification: If the wiring tests good (no short to power, good ground, and proper 5V reference voltage), the sensor itself is internally shorted and must be replaced.

1. 1

   Turn off the machine, remove the key, and allow the engine to cool.

2. 2

   Locate the Boost Pressure Sensor on the engine intake manifold.

3. 3

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

4. 4

   Remove the retaining fastener(s) holding the sensor to the intake manifold.

5. 5

   Carefully pull the old sensor out, ensuring that no dirt or debris falls into the intake manifold opening.

6. 6

   Lubricate the O-ring on the new sensor with a small amount of clean engine oil to prevent tearing during installation.

7. 7

   Push the new sensor into the manifold port and tighten the retaining fastener.

8. 8

   Reconnect the electrical connector, ensuring it clicks securely into place.

9. 9

   Turn the key on, use a diagnostic tool (such as Jaltest or CNH Electronic Service Tool) to clear the ENG 122 fault code, and start the engine to verify the code does not return.