Case IH 19156 (DTC 335A) - ECU – Engine ECU: DEF/AdBlue supply module pump motor severe speed deviation

The control module monitors the reductant pump motor speed. If the difference between the commanded pump speed and the actual monitored pump speed exceeds a specific threshold (e.g., 300 rpm), this DTC is set. This typically indicates that the pump is overspeeding, failing to deliver fluid properly, or cavitating due to drawing air. When this code triggers, the Selective Catalytic Reduction (SCR) system will shut down, and the engine will eventually enter a derated power mode.

• MAXXUM T4E
• 240 Series Axial-Flow (7240, 8240, 9240)
• 140 Series
• 5130
• 6130
• 7130
• Steiger (350, 400, 450 SCR, 500, 550, 600)
• Magnum 235-340 (Series 4)
• Maxxum
• Puma
• Farmall
• Patriot (4430)
• Titan
• Farmlift

1. 1

   Check the DEF supply module wiring for defects. Look for high resistance in the VPWR (power) circuit, high resistance in the GND (ground) circuit, or a short to ground.

2. 2

   Inspect the DEF suction tubes and lines. A crack in the suction tube (even at the very top of the tank) can cause the pump to draw air instead of fluid, leading to a loss of prime and severe pump overspeed.

3. 3

   Inspect the surrounding area of the pump housing for dried white urea crust and dust, which can indicate a leak or contamination.

1. 1

   Clear Codes

   Clear the active codes and cycle the key to see if the fault returns immediately.

2. 2

   Verify Wiring

   If the wiring harness and connectors are damaged or loose, repair them. If the fault is not active with a replacement/test ECU, the original ECU may be defective (though rare).

3. 3

   Replace the DEF Supply Module

   If the wiring is intact, no air leaks are found in the suction lines, and the code persists, the reductant pump assembly (DEF supply module) is internally damaged and must be replaced.

4. 4

   Prep for Replacement

   Ensure the surrounding area is completely clean of dried urea crust before opening any caps or lines. If flushing the external housing face, use only clean distilled water to safeguard the internal high-pressure fluid loops.

5. 5

   Programming

   Note that a new Bosch DEF supply module/dosing module will likely need to be programmed/calibrated to the vehicle's ECU after installation using a diagnostic scan tool.