bulbs work. If any light remains on after starting the vehicle, refer to the
respective system warning light description for additional information.
Note: Some warning lights are
reconfigurable telltale (RTT)
indicator lights and will illuminate in
the message center. These lights
function the same as the other
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 have your vehicle serviced
immediately by your authorized dealer.
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.
2010 F-250/350/450/550 (f23)
Owners Guide, 1st Printing