Skip the auto shop - Our mechanics make house calls

Q: The car has a decrease in gas mileage

asked by on

I have a well-maintained car that has been running great with no major problems. Except for the poor gas mileage issue, for which I went to the dealership but was told that nothing is wrong. This problem started occuring several months ago. Up to now, the miles per gallon decreased 23% and I would like to know why. I haven't changed anything in my driving habits so this is very unusal. What could cause this? What can I do to improve gas mileage?

Hello. For a sudden drop like this to occur, it usually means that a sensor it not reading correctly. I usually install a scan tool first to check things like the oxygen sensors and the air flow meter as they are the most common causes of a drop in MPG. If nothing is found, then I clean out the air flow meter and reset the computer and that usually takes care of it. If you need to have this checked, consider YourMechanic, as a certified mechanic can come to your home or office to inspect your fuel system and let you if any adjustments or repairs should be made. It is possible that the decrease in MPG could merely be a result of a change in recent driving habits.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I have a 2003 Cadillac CTS manual, I need a computer and a buddy is selling me his from an 03 Cadillac CTS automatic. Will it work

Hi there. In short; no - this will not work. The only way it would possibly work is if you took your new ECU to Cadillac dealership and have them reprogram the new ECU to your individual car's specs and...

Q: Car shuts off, smoke and black water from muffler

The color of the smoke can point us in the right direction of the problem. Blue or purple smoke indicates oil burning in the combustion chamber and can be caused my weak piston rings, worn valve seals or a malfunctioning...

Q: Timing belt broke

Hello. It sounds like you have interference motor that will need to be replaced. An interference motor is one that has very tight valve clearance between the cylinder head and the engine piston. If the timing belt breaks in this...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...