New Holland ENG 3790:

Inspect the DPF differential pressure sensor and physical hoses for blockages (soot buildup), melting, cracks, or disconnected lines

Check the wiring harness and connectors for the differential pressure sensor for corrosion, moisture, or crushed wiring looms that can cause false 'Max' readings

Use a diagnostic tool to read the current soot load values and check when the last successful regeneration occurred

Check for accompanying codes related to the EGR system or turbocharger (a malfunctioning EGR valve increases soot production and rapidly clogs the DPF)