Mechanical Issues:

• Load Cell Damage:Load cells are the core components of the weighing system. Damage from overloading, impact, or corrosion can lead to inaccurate readings.  
• Pivot Wear and Tear:Moving parts in the weighing mechanism can wear down over time, affecting accuracy and stability.
• Structural Instability:Shifts in the foundation or supporting structure can cause the weighbridge to become uneven, leading to inaccurate measurements.

Environmental Factors:

• Temperature Fluctuations: Extreme temperatures can affect the performance of electronic components and the calibration of the system.  
• Wind and Vibration:Strong winds or vibrations can cause slight movements of the vehicle on the weighbridge, leading to inconsistent readings.  
• Moisture and Corrosion:Exposure to moisture can corrode electrical connections and damage load cells, impacting accuracy and reliability.  

Calibration and Maintenance:

• Improper Calibration:Inaccurate or infrequent calibration can lead to significant errors in weight measurements.
• Lack of Regular Maintenance:Neglecting regular maintenance, such as cleaning and lubrication, can accelerate wear and tear and increase the risk of malfunctions.  

Human Error:

• Operator Errors:Incorrect data entry, improper vehicle positioning, or distractions can lead to inaccurate weighing results.
• Tampering:Attempts to manipulate weight readings for fraudulent purposes can compromise the integrity of the weighing system.

I guess you might also want to read the article about Beyond the Scale: Exploring Weighbridge Applications, Varieties, and Processes.