Take the appropriate action and verify that the warning light turns off.

Taking Action
Message Indicated on DisplayMazda 6 Owners Manual: Turn Signals
Move the signal lever down (for a left turn) or up (for a right turn) to the stop position. The signal will self-cancel after the turn is completed.
If the indicator light continues to flash after a turn, manually return the lever to its original position.
The turn signal indicators in ...
Mazda 6 Owners Manual: Front door trim removal/installation
1. Disconnect the negative battery cable.
2. Open the cap using a small screwdriver, then remove the screw.
3. Remove the inner handle cover.
4. Remove the inner garnish.
5. Remove the cover, then remove screw A.
6. Remove the lens cover, then remove screw B.
7. Disengage clips A from the ...