What are the reasons for the OBD warning light in diesel vehicles?

[MacColin]

Diesel vehicle OBD light on indicates excessive tailpipe emissions or engine malfunction. Below is relevant information about the OBD light: 1. Meaning: OBD stands for On-Board Diagnostics, an onboard automatic diagnostic system. It appears on the dashboard as a symbol resembling a water tap, also referred to as the engine warning light. More importantly, OBD continuously monitors the engine's operating conditions to detect if the vehicle's emissions exceed standards, issuing an immediate alert if they do; 2. OBD light on: Generally, the OBD light being on rarely prevents the vehicle from starting, meaning the car can still be driven.