Fault Phenomenon: SANY SY5410THB exhaust is normal when cold. After long-term use (operating temperature), the urea nozzle crystallizes, engine torque is limited, and power eventually drops.

Troubleshooting Process:
– Checked urea solution: concentration normal.
– Checked urea pump: pump works normally.
– Checked nozzle heating: heating function normal.
– Measured nozzle back pressure at operating temperature: found excessive back pressure.

Root Cause: The urea nozzle heating element fails, causing residual urea to crystallize and block the nozzle.

Required Parts: Urea nozzle assembly and heating element.