Diagnostic Trouble Code(s) (DTC): Notes

WARNING: This page is about a different car, the 2021 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

DTC is a code consisting of 9-digit alphanumeric characters which are stored when each module detects a malfunction.
The first 5 digits of the DTC indicate which system or part and what kind of malfunction is occurring. Digits 6 to 7 add more detailed information on the malfunction content (such as open/short circuit, characteristic malfunction).
The last 2 digits of the DTC are called status byte indicating malfunction conditions such as pending code, past/current malfunctions, and the warning light illumination condition.

Courtesy of MAZDA MOTORS CORP.