What changes
Unit 09, object 0A5E: byte 2, bit 6 = 1. On emergency braking the hazard lights switch on automatically to warn the traffic behind.
Details
Setting of the newer MQB body control module. The trigger threshold is set by the module from the deceleration — usually hard braking from a noticeable speed; normal braking is unchanged. On the older module the same option is object 0D21, byte 1, bit 6, so a3c refuses there before writing. Unit 09 on MQB Evo is SFD-protected — a token for unit 09 is needed. Roll back by writing the object backup from history.