Mazda 6 Service Manual: No.7 slow return to idle

No.6 cranks normally but will not start

No.8 engine runs rough/rolling idle

Other materials:

Mazda 6 Service Manual: Dtc clearing procedure
1. Start the on-board diagnostic test mode. 2. First press the POWER button, then simultaneously press AUDIO CONT button for 2 seconds or more. Caution Before clearing the DTCs, be sure to enter all of them displayed in the on-board diagnostic test mode in the Audio Repair Order Form. ...

Mazda 6 Service Manual: To Operate the System
The High Beam Control System (HBC) operates to switch the headlights automatically between high and low beams after the ignition is switched ON and the headlight switch is in the AUTO and high beam position. The High Beam Control System (HBC) determines that it is dark based on the brightness ...