Best OBD fault code reader K12

I have an issue with my Mums K12 and NATS being stuck on. Need to troubleshoot it and see if I can find the exact problem.

I already own a VAG ODBII USB cable. What am I better off purchasing?


or a cheap reader like this:

The goal is to see if its the EPS code and I have also read that someone had a similar not start issue and fixed it just by clearing the fault codes.