Ford Mustang Owner's Manual page 13

Service engine soon: The service
engine soon indicator light
illuminates when the ignition is first
turned to the on position to check
the bulb and to indicate whether the vehicle is ready for
Inspection/Maintenance (I/M) testing. Normally, the service engine soon
light will stay on until the engine is cranked, then turn itself off if no
malfunctions are present. However, if after 15 seconds the service engine
soon light blinks eight times, it means that the vehicle is not ready for
I/M testing. See the Readiness for Inspection/Maintenance (I/M)
testing in the Maintenance and Specifications chapter.
Solid illumination after the engine is started indicates the On Board
Diagnostics System (OBD-II) has detected a malfunction. Refer to On
board diagnostics (OBD-II) in the Maintenance and Specifications
chapter. If the light is blinking, engine misfire is occurring which could
damage your catalytic converter. Drive in a moderate fashion (avoid
heavy acceleration and deceleration) and contact your authorized dealer
as soon as possible.
WARNING: Under engine misfire conditions, excessive exhaust
temperatures could damage the catalytic converter, the fuel
system, interior floor coverings or other vehicle components, possibly
causing a fire.
Brake system warning light: To
confirm the brake system warning
light is functional, it will
momentarily illuminate when the
ignition is turned to the on position
when the engine is not running, or in a position between on and start, or
by applying the parking brake when the ignition is turned to the on
position. If the brake system warning light does not illuminate at this
time, contact your authorized dealer as soon as possible. Illumination
after releasing the parking brake indicates low brake fluid level. Contact
your authorized dealer as soon as possible.
2011 05+ Mustang (197)
Owners Guide, 1st Printing
USA (fus)
Instrument Cluster
! P
BRAKE
13