Why does the engine malfunction light come on after replacing the catalytic converter?

[VanAubree]

Replacing the catalytic converter and having the engine malfunction light come on is most likely caused by the engine's mixture being either too rich or too lean. Here is more relevant information: 1. Precautions for using the automotive catalytic converter: Check the working condition of the oxygen sensor every 30,000 km. If it shows signs of aging or failure, clean or replace the oxygen sensor promptly. This is because both the catalytic converter and engine performance can be damaged due to a malfunctioning oxygen sensor—don't risk major damage for minor savings. 2. How the catalytic converter works: When high-temperature exhaust gases pass through the purification device, the catalyst in the catalytic converter enhances the activity of CO, HC, and NOx gases, promoting specific oxidation-reduction reactions.