On-board Diagnostics (OBD-II)
Your vehicle is equipped with a computer that monitors the engine’s
emission control system. This system is commonly known as the
on-board diagnostics system (OBD-II). The OBD-II system protects the
environment by ensuring that your vehicle continues to meet
government emission standards. The OBD-II system also assists your
authorized dealer 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 are:
1. The vehicle has run out of fuel—the engine may misfire or run poorly.
2. Poor fuel quality or water in the fuel—the engine may misfire or run
poorly.
3. The fuel fill inlet may not have been properly closed. SeeEasy Fuel®
No Cap Fuel Systemin this chapter.
4. Driving through deep water—the electrical system may be wet.
These temporary malfunctions can be corrected 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 the engine is started. A driving cycle
consists of a cold engine start-up followed by mixed city or 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 can 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.
Fuel and Refueling159
2014 MKX(mkx)
Owners Guide gf, 2nd Printing, March 2014
USA(fus)
