Bad gas mileage on the Accord?

Discussion in 'Honda' started by CivilGuy, Dec 22, 2017.

  1. CivilGuy

    CivilGuy New Member

    Hey folks, how is it going.
    Something's wrong with my Accord in terms of gas mileage, so wanted to ask you for ideas on what I have to search for. It is a 2013 Accord, 3.5 L V6 24 v, automartic. Not sure, what else you need to know about it. Now, the normal gas mileage for it, based on my calculations, is around 20 mpg (city). Now, it dropped to 15! Man, that's too bad, and you know, there's nothing I have done about it before, you know, no repairs/maintenance so far. And I keep buying teh same gas at the same gas station, so I need an idea on what may be wrong with it, please.
    BillLin likes this.
  2. S Keith

    S Keith Well-Known Member

    Cold weather?
    Excessive idling during warm-up?

    Look for changes to environment/habits/drivers before you assume it's the car.
    BillLin likes this.
  3. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    Welcome to CleanMPG!

    Is this a new-to-you car or one you've had over a year? How was it last winter?
  4. CivilGuy

    CivilGuy New Member

    I bought it in September 2015, so this is the second winter for us both...
    I've checked the codes at the shop, and guy determined the oxygen sensor failed.
    Now, I was thinking of the Denso sensor, is it a good idea to try one? (here it is)
    Or it's better to pay more and get the one from the Honda dealer?
    BillLin likes this.
  5. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    Sorry, I can't help you with that comparison. If it were me, I would not hesitate to try that swap myself. Price seems right and the task should be not too difficult.

    Glad you found the likely cause...
  6. S Keith

    S Keith Well-Known Member

    You'll need an O2 sensor socket. It's basically a deep well with a slot along one side to accommodate the wire/connector.

    It's usually pretty easy to do depending on if you can access it. I wouldn't buy OEM, but I would make certain to buy the aftermarket version from the same manufacturer, i.e., if Denso makes it for the OEM, then they will usually have the exact one but with a Denso part number. Honda upper O2 sensors are notoriously expensive - even when going the route I described. Don't make the mistake of buying the wrong one. You will sacrifice either function or longevity.
    BillLin likes this.
  7. S Keith

    S Keith Well-Known Member

    Few things after some research - First, there are at least four O2 sensors on your car. Front and rear upper and lower.

    What you have listed is the front downstream sensor. Downstream sensors relate to measuring emissions performance and less to economy. Failure of the upstream sensors impacts the feedback loop and causes "limp" modes or forces the car to run in a richer condition.

    Upstream sensor monitors the exhaust coming out of the manifold and feeds that info back to the computer for mixture adjustment. The downstream sensor monitors whats coming out of the upper catalytic converter to measure cat performance.

    Before you do anything, you need to know the codes the car is throwing, or this is likely going to be an exercise in frustration.

    There are also different upstream sensors for California cars.

    I recommend you do nothing until you know which sensor(s) to replace. When the time comes, you can get the correct part numbers here:
    BillLin likes this.
  8. puddleglum

    puddleglum Well-Known Member

    Don't think you can go wrong with Denso parts. The Honda sensor is likely a Denso in a Honda box anyway. S Keith is right though, you need to know which one. Did tech tell you the code or which sensor exactly?
    BillLin likes this.

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