Case IH 19043 (F-354-04) - ECU – Engine Control Unit (ECU): Intake air humidity sensor voltage is lower than expected

The Engine Control Unit (ECU) is receiving a voltage signal from the intake air humidity sensor that falls below the minimum acceptable threshold (Voltage Below Normal / Shorted to low source).

• VESTRUM CVX
• 240 Series Axial-Flow® Combines (7240, 8240, 9240)
• Magnum Tractors (250-380 series)
• Steiger Tractors
• Puma Tractors
• Farmall Tractors (40, 45, 50, 85C, 95C, 105C)
• N Series Loaders

1. 1

   Locate the intake air humidity sensor in the inlet air plumbing between the air filter and the turbocharger

2. 2

   Check the sensor element and the intake tract for excessive condensation or water droplets (a common cause for this code)

3. 3

   Inspect the wiring harness between the intake air humidity sensor and the Engine ECU for a short circuit to ground or chafed wires touching the chassis

4. 4

   Inspect the connector by disconnecting the sensor and checking the pins for corrosion, pushed-back terminals, or trapped moisture

1. 1

   Power Down

   Turn off the engine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Intake Plumbing

   Locate the intake air humidity sensor on the air intake pipe, situated between the main air filter housing and the turbocharger inlet.

3. 3

   Inspect and Clean

   Disconnect the electrical harness from the sensor. If water droplets or moisture are present inside the connector or on the sensor tip, dry it thoroughly using compressed air.

4. 4

   Test the Circuit

   Use a multimeter to verify there is no short to ground on the signal wire leading back to the ECU. If a short is found, repair the damaged section of the wiring harness.

5. 5

   Replace the Sensor

   If the wiring is intact, the connector is clean/dry, and the code persists, the sensor itself has failed internally and must be replaced. Remove the mounting screws/clip, pull the old sensor out of the intake pipe, and install the new sensor.

6. 6

   Clear Codes

   Reconnect the battery, turn the key on, and use a diagnostic scan tool to clear the inactive 19043 fault code. Run the engine to verify the code does not return.