What Causes the Yellow Engine Light to Illuminate in BMW?

[VonColeman]

There are many reasons for the yellow engine light to illuminate in a BMW, which can generally be categorized into the following three types: 1. False alarm. A fault code is reported, but the engine operates normally. This may be due to an operation that temporarily exceeded the computer's control range, causing the computer to feedback a fault code. The code can be cleared first, and then observe whether the fault code reappears. 2. Minor fault. The engine does not show any obvious issues, but further inspection based on computer diagnostics reveals an actual fault that does not affect or minimally affects normal driving. It should be identified and resolved promptly. Examples include faults with the intake pressure sensor. 3. Major fault. Such faults can be detected visually or through driving experience and severely impact the engine's normal operation, requiring immediate repair. For instance, significant loss of engine power may indicate an issue with the oxygen sensor, among others.