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My 2009 Honda CRV seems to be getting worse than normal fuel efficiency. The gas bars disappear quicker than it used to.

I have tried the following:

  • New spark plugs
  • New air filter
  • Oil change
  • A cheap fuel line cleaner added to a tank of gas

all of which seem to have made no difference.

Additionally my "Vehicle Stability Assist" (VSA) light is on, could this be related?

What else could I try?

  • Welcome to Motor Vehicle Maintenance & Repair! – Pᴀᴜʟsᴛᴇʀ2 Dec 11 '17 at 19:12
  • This lacks detail - how much is the change 5mpg less or 20mpg less - once you give some definitive figures it may be possible to point you in a direction. Otherwise it could be simple like low tyre pressures, or a change to the daily commute... – Solar Mike Dec 11 '17 at 19:28
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    It could be running too rich (engine is given too much fuel), making for more fuel consumption. If your exhaust smells somewhat like unburned fuel, if it produces lightly blackish smoke, or if it sounds somewhat deeper than normal, this could be the issue.This can be caused by eg. a faulty oxygen sensor or throttleposition sensor. Those should bring up your CEL light though, if detected. Furthermore, you could check if your wheels can rotate freely, so that no bearing or brakes robs engine power and thus fuel. – Bart Dec 12 '17 at 21:58
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The most common source of reduced fuel mileage is low tire pressure. However, there are MANY other things that could contribute to worse than normal fuel economy. The VSA light on in your car means there is a malfunction with the "Vehicle Stability Assist" system. I would suggest to start with fixing things you know are wrong with your vehicle like whatever is causing this VSA light.

For future reference here is how to do a proper fuel consumption test. Pick a certain pump at a certain gas station. Use this same pump for every test you want to conduct. Fill your vehicle till the pump shuts off automatically. Don't top off fuel after this point. Note your mileage (or kilometers) and drive till its time to refuel again. Note your vehicle's mileage when you refuel at the previously used gas pump. Finally, note the volume of gas the pump reads after it shuts off automatically and use this formula:

(end mileage - start mileage)/ volume refilled = fuel economy

Note: Don't buy into these "mechanic in a can" products like gas station fuel system cleaner. There is a time and place for similar products on certain vehicles but not all. Ask your mechanic before potentially wasting your money on such products.

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