New Holland 3545 – ECU: SCR Dosing Valve Overheat Protection Activated

The Selective Catalytic Reduction (SCR) Dosing Valve (also known as the metering valve or DEF injector) has exceeded a safe operating temperature. The system has detected that the torque level limit 2 has been reached, triggering the overheat protection of the SCR metering valve. This indicates that the component is operating under conditions that may lead to overheating. To protect the valve from damage, the Engine Control Module (ECM) activates a significant reduction in engine power (limp mode) to force the operator to address the issue.

• T7.270
• T8.275
• T8.300
• T8.330
• T8.360
• T8.390
• T8.420
• CR6090
• CR7090
• CR8.90
• CR8080
• CR8090
• CR9.90
• CR9090
• CX8.90
• CX8070
• CX8080
• CX8090
• SP.2240
• Farmlift Telehandlers
• Magnum 225
• Magnum 235
• Magnum 340
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 9230

1. 1

   Check for other active fault codes related to temperature sensors, NOx sensors, or DPF restrictions that could indicate the root cause of the overheat

2. 2

   Inspect DEF quality and level, ensuring the tank is filled and urea concentration is approximately 32.5% using a refractometer

3. 3

   Inspect the DEF dosing valve and injector port for white crystal buildup, nozzle blockages, or carbon and soot buildup in the exhaust port

4. 4

   Verify DEF flow and line integrity by checking for kinks, loops, restrictions, or blockages in the DEF filter

5. 5

   Inspect the exhaust and aftertreatment system for leaks upstream of the SCR catalyst, or a clogged/failing DPF or DOC

6. 6

   Check exhaust gas temperature sensors for faulty readings that could lead to improper system operation

1. 1

   Prepare machine for service

   Park on a level surface, shut down the engine, engage the parking brake, and disconnect the battery. Allow the exhaust system to cool completely.

2. 2

   Access the dosing valve

   Remove any heat shields or access panels to gain clear access to the SCR dosing valve mounted on the exhaust system.

3. 3

   Disconnect lines and connectors

   Wait at least five minutes after engine shutdown for the system to purge. Disconnect the main electrical connector from the dosing module and inspect the connector for corrosion or damage. Carefully disconnect the DEF supply and return lines. Be prepared for some residual DEF to spill and use a container to catch it. Squeeze the locking tabs on the elbow connectors to release them.

4. 4

   Remove the dosing valve

   Remove the bolts (typically three) securing the dosing valve to its mounting plate on the exhaust. Remove the old valve and discard the gasket.

5. 5

   Install new dosing valve

   Thoroughly clean the mounting surface on the exhaust pipe to ensure a proper seal. Place a new gasket on the new dosing module, install the valve, and tighten the mounting bolts to the manufacturer's specified torque. Do not overtighten, as this can damage the gasket.

6. 6

   Reconnect components

   Reconnect the DEF supply and return lines until they click securely. Reconnect the electrical connector, reinstall heat shields, and reconnect the battery.

7. 7

   Prime system and verify repair

   Start the engine and use a diagnostic tool to perform a DEF system priming function to check for leaks. Clear all fault codes and run the machine under load (a forced regeneration may be necessary) to verify the code does not return.