If your fuel economy is excessively low, your vehicle may need to be serviced or repaired. You may want to contact your dealer or a reputable repair facility to check your vehicle. The following are some of the diagnostic checks a mechanic will typically conduct for poor MPG:

  1. Perform "On-Board Diagnostic System Check" for diagnostic trouble codes (sensors or actuators which may be malfunctioning)
  2. Check for dragging brakes
  3. Check transmission shift patterns for slipping, use of all gears, lock-up operation
  4. Check ignition timing
  5. Check owner's driving habits including A/C usage, hard accelerations, carrying heavy loads
  6. Check emission control system
  7. Check vacuum hoses for leaks, kinks, proper routing
  8. Check tire pressure
  9. Check fuel type, quality, and alcohol content
  10. Check fuel pressure and fuel system for leaks
  11. Check air cleaner element
  12. Check coolant level
  13. Check ignition system for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits, cracking or improperly connected ignition wires
  14. Check for proper calibration of speedometer
  15. In extreme cases, there may be engine problems such as poor compression or faulty fuel injectors