Case IH t35 – Engine Control Unit (ECU): Boost Air Pressure Sensor (PHY), Data Valid But Above Normal Range

The sensor is transmitting a valid electrical signal, but the pressure value it is reading exceeds the maximum expected threshold for normal engine operation. This typically points to an actual mechanical overboost condition (such as a stuck turbo wastegate), a restricted intake/intercooler system, or a sensor that has drifted out of calibration and is reading artificially high.

• MXM
• MXM Series
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190
• Maxxum Series
• Puma Series
• TM Series
• TM120
• TM130
• TM140
• TM155
• TM175
• TM190
• T6 Series
• T7 Series

1. 1

   Inspect the 4-terminal electrical connector at the boost pressure sensor for corrosion, moisture, or backed-out pins that could cause high resistance and skew data

2. 2

   Inspect the turbocharger wastegate to ensure it is not mechanically stuck closed (this would cause a genuine mechanical overboost condition)

3. 3

   Check the intercooler, intake manifold, and air filters for blockages or heavy carbon/oil buildup that could restrict airflow and cause abnormal pressure spikes

4. 4

   Compare the live Boost Pressure Sensor reading to the Atmospheric/Barometric Pressure Sensor with the engine off using an Electronic Service Tool (EST). If the boost sensor reads significantly higher, the sensor has failed

1. 1

   Turn off tractor

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

2. 2

   Locate sensor

   Locate the Boost Air Pressure Sensor. It is mounted directly on the intake manifold, typically near the turbocharger or intercooler piping.

3. 3

   Disconnect harness

   Depress the locking tab and disconnect the 4-wire electrical harness from the sensor.

4. 4

   Remove mounting bolts

   Remove the two mounting bolts securing the sensor to the manifold.

5. 5

   Remove sensor

   Pull the sensor straight out.

6. 6

   Clean mounting surface

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

7. 7

   Install new sensor

   Lubricate the O-ring on the new sensor slightly with clean engine oil, insert it into the manifold, and tighten the two mounting bolts.

8. 8

   Reconnect harness

   Reconnect the electrical harness.

9. 9

   Clear codes and test

   Turn the key on and clear the fault codes using the tractor's H-Menu/calibration sequence or a diagnostic tool. Test run the machine under load to ensure the code does not return.