Case IH F-3363-31 - ECU – Engine Control Unit (ECU): DEF tank heater coolant valve low side power stage over temperature / DEF tank heating valve - Valve stuck closed

The ECU has detected an overheating condition on the power circuit controlling the DEF tank heater coolant valve, or the directional valve itself is physically stuck closed. Because the valve cannot open, hot coolant is prevented from circulating, and the system fails to defrost the urea tank within the programmed time limit.

• MAGNUM AFS Connect
• Magnum (180-370)
• Steiger (350-600)
• Puma (130-215)
• Maxxum (110-140)
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Patriot (4430)
• Titan (3030-4530)
• Farmlift series
• SV/TV series skid steers

1. 1

   Inspect Coolant Hose Routing: Check the DEF tank coolant hoses. Ensure the DEF heater line with the 'red' band is connected to the top tube running to the front part of the engine head.

2. 2

   Test the Heater Control Valve: Use a diagnostic tool to command the valve open and closed. Verify if the valve is physically stuck or if it operates intermittently.

3. 3

   Check Wiring and Relays: Inspect the wiring harness leading to the coolant control valve for shorts to ground, shorts to a high source, or open circuits.

4. 4

   Check ECU Software Version: Ensure the tractor's ECU is flashed with the latest software (e.g., Service Bulletin 2014-005 CIH N SB) to address issues where the DEF thawing logic was too aggressive or timed out incorrectly in cold weather.

1. 1

   Prepare the Machine

   Park the machine on a level surface, turn off the engine, and allow the engine coolant to cool down completely to avoid burns.

2. 2

   Drain Coolant

   Partially drain the engine cooling system to bring the fluid level below the DEF tank heater control valve to prevent spills.

3. 3

   Disconnect the Valve

   Locate the DEF tank heater coolant control valve. Disconnect the electrical harness connector from the valve.

4. 4

   Remove Hoses

   Mark the orientation of the coolant hoses (specifically noting the hose with the red band) and disconnect them from the valve.

5. 5

   Replace the Valve

   Remove the mounting hardware holding the defective valve and install the new OEM replacement valve.

6. 6

   Reassemble

   Reconnect the coolant hoses in the correct directional orientation. Reconnect the electrical harness.

7. 7

   Refill and Bleed

   Refill the engine coolant to the proper level and bleed any air from the cooling system.

8. 8

   Clear Codes and Update

   Connect the Case IH Electronic Service Tool (EST). Clear the F-3363-31 fault code. If the machine does not have the latest SCR/DEF software update, flash the ECU to prevent future cold-weather logic errors.

9. 9

   Test Operation

   Run the machine and verify that the valve opens and hot coolant circulates to the DEF tank without throwing a code.