Massey Ferguson U 698 – Engine ECU: Discharge heating power supply / Cooling line heater power stage error

An electrical failure in the power supply to the discharge/cooling line heater of the DEF/AdBlue system. This causes the tractor's electronic system to activate an 'Emergency operation' derate mode, limiting engine power to 60% and capping maximum engine speed at 1500 rpm.

• 8600 Series
• 8650
• 8660
• 8670
• 8680
• 8690

1. 1

   Identify the sub-code (3, 5, or 6) on the instrument panel to determine if the fault is a short to battery, open load, or short to ground.

2. 2

   Visually inspect the insulated DEF heated lines running from the pump module to the doser/injector for kinks, rub points against the chassis, or melted insulation.

3. 3

   Inspect the electrical quick connectors for the heater circuit for corrosion, dirt, or backed-out pins that could cause an open load.

4. 4

   Use a multimeter to test the resistance of the heating element inside the line. If it reads infinite resistance, the heating element is burnt out.

1. 1

   Preparation

   Turn off the tractor and disconnect the battery to prevent electrical shorts during the repair. Ensure the exhaust system has cooled down.

2. 2

   Access the Lines

   Locate the faulty DEF discharge line. Note its exact routing path, as improper routing of the new line will lead to premature failure.

3. 3

   Disconnect Electricals

   Unplug the electrical connector supplying power to the line heater.

4. 4

   Disconnect Fluid Lines

   Release the quick connectors securing the DEF line. Clean up any spilled DEF immediately, as it is highly corrosive to metal components.

5. 5

   Remove and Replace

   Remove the damaged line. Install the new heated line assembly, ensuring it is routed strictly away from hot edges and sharp rub points.

6. 6

   Seal and Secure

   Reconnect the fluid quick connectors. Ensure the internal O-rings are seated properly and not nicked, as air ingress can cause subsequent priming faults.

7. 7

   Finalize

   Reconnect the electrical harness and the battery. Turn on the ignition and use the instrument panel or a diagnostic tool to clear the fault codes. Start the engine to verify the 1500 rpm / 60% power derate has been lifted.