Case IH 19516 – Engine Control Unit (ECU) / Engine Control Module (ECM): Intake air humidity is too high.

The Intake Air Humidity and Temperature Sensor detects a humidity value above the maximum plausible limit, which can be caused by actual water in the intake, a saturated sensor, or an electrical short. This data is critical for calculating raw engine NOx production and adjusting the DEF/AdBlue injection rate.

• Tier 4b
• Case IH Magnum series
• Case IH Steiger series
• Case G-Series (521G, 621G, 721G, 821G)
• Case N-Series (580N, 580SN, 590SN)

1. 1

   Check for water ingress in the engine air filter housing and intake piping (e.g., from heavy rain, aggressive washing, or compromised housing).

2. 2

   Remove and inspect the sensor element for physical water droplets or debris that could falsely report maximum humidity.

3. 3

   Inspect the sensor's electrical connector and wiring harness for corrosion, bent pins, or a short circuit to an external voltage source.

1. 1

   Power Down

   Turn off the machine, remove the key, and switch off the master battery disconnect.

2. 2

   Locate the Sensor

   Locate the Intake Air Humidity Sensor. It is installed directly in the engine's intake air piping, positioned between the main engine air filter and the turbocharger/intake manifold.

3. 3

   Address Moisture

   If you found water in the intake tract during your diagnostics, dry out the intake piping and replace the primary and secondary engine air filters.

4. 4

   Remove the Sensor

   Disconnect the electrical wiring harness from the sensor. Unbolt or unthread the sensor from the intake pipe.

5. 5

   Install the New Sensor

   Insert the replacement Intake Air Humidity Sensor into the intake piping and secure it.

6. 6

   Reconnect

   Plug the electrical connector back into the sensor, ensuring the weather seal clicks firmly into place.

7. 7

   Clear Codes

   Turn the master battery switch back on. Connect a diagnostic service tool (such as the CNH Electronic Service Tool - EST) to the machine and clear the inactive 19516 fault code.

8. 8

   Test Run

   Start the engine and run the machine under load to verify that the fault code does not return and that the DEF dosing system is operating normally.