On-Board Diagnostics (OBD-II)
Your vehicle has a computer known as the
on-board diagnostics system (OBD-II) that
monitors the engine’s emission control
system. The system protects the
environment by making sure that your
vehicle continues to meet government
emission standards. The OBD-II system
also assists a service technician in properly
servicing your vehicle.
When the service engine soon
indicator illuminates, the OBD-II
system has detected a
malfunction. Temporary malfunctions may
cause the service engine soon indicator to
illuminate.
Examples of temporary malfunctions are:
• the vehicle has run out of fuel—the
engine may misfire or run poorly
• poor fuel quality or water in the
fuel—the engine may misfire or run
poorly
• the fuel fill inlet may not have closed
properly. See Refueling (page 131).
• driving through deep water—the
electrical system may be wet.
You can correct these temporary
malfunctions by filling the fuel tank with
good quality fuel, properly closing the fuel
fill inlet or letting the electrical system dry
out. After three driving cycles without these
or any other temporary malfunctions
present, the service engine soon indicator
should stay off the next time you start the
engine. A driving cycle consists of a cold
engine startup followed by mixed
city/highway driving. No additional vehicle
service is required.
If the service engine soon indicator remains
on, have your vehicle serviced at the first
available opportunity. Although some
malfunctions detected by the OBD-II may
not have symptoms that are apparent,
continued driving with the service engine
soon indicator on can result in increased
emissions, lower fuel economy, reduced
engine and transmission smoothness, and
lead to more costly repairs.
Readiness for
Inspection/Maintenance (I/M)
Testing
Some state/provincial and local
governments may have
Inspection/Maintenance (I/M) programs
to inspect the emission control equipment
on your vehicle. Failure to pass this
inspection could prevent you from getting
a vehicle registration.
If the service engine soon
indicator is on or the bulb does
not work, you may need to have
the vehicle serviced. See On-Board
Diagnostics (OBD-II).
Your vehicle may not pass the I/M test if
the service engine soon indicator is on or
not working properly (bulb is burned out),
or if the OBD-II system has determined
that some of the emission control systems
have not been properly checked. In this
case, your vehicle is not ready for I/M
testing.
If the vehicle’s engine or transmission has
just been serviced, or the battery has
recently run down or been replaced, the
OBD-II system may indicate that the
vehicle is not ready for I/M testing. To
determine if the vehicle is ready for I/M
testing, turn the ignition key to the on
position for 15 seconds without cranking
135
Focus (CDH) Canada/United States of America, enUSA, First Printing
Fuel and Refueling
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