To my knowledge, there are codes that can be set, that regular code readers will not read. You would need the manufacturers diagnostics to read those out, or aftermarket alternative. I don't know if it applies, but ABS and SRS codes are not included in many readily available code readers. These are usually referred to as the "Enhanced" codes. I used to have the AutoTap version of computer software to read these for all US manufacturers. However, they no longer support that software.