What Causes the OBD Warning Light to Illuminate?
1 Answers
OBD warning light illuminates due to: 1. Oxygen sensor malfunction; 2. Three-way catalytic converter issues such as leaks, blockages, damage, or reduced catalyst performance. A yellow OBD warning light on the dashboard indicates non-compliant emissions or incomplete combustion. OBD stands for On-Board Diagnostics, a system that continuously monitors the engine's operating conditions and the exhaust after-treatment system's performance. It immediately alerts if any condition that may cause excessive emissions is detected. When a system fault occurs, the Malfunction Indicator Lamp (MIL) or Check Engine warning light turns on, and the Powertrain Control Module (PCM) stores the fault information in memory. The fault code can be retrieved from the PCM using specific procedures. Based on the fault code, maintenance personnel can quickly and accurately identify the nature and location of the fault.