U0121 Mazda 6 how do I check this and fix it?

Question

Won't pass smog with this code u0121

Answer 1

Hi there

This code points to a problem with communication with the ABS computer and the ECM.

Here is some info on the code for you.

U0121 - Lost Communication With Electronic Brake Control Module

Read more: https://www.autocodes.com/u0121.html