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I recently purchased a 2003 base Outback wagon with 123,000 miles. It wasn't well maintained and has many issues, but runs okay. It's managed decent gas mileage in the months I've had it but my MPGs have dropped dramatically in the last two weeks. A google search mentioned a possible cause of sudden bad gas mileage being a parking brake that didn't release. Has anyone experienced this? I did use my emergency brake recently (maybe for the second or third time since purchase) and I did release it. The parking brake lever is in the down position, but is it possible the brake itself is still engaged? I have noticed a new feeling of resistance when I'm driving. If so, what needs to be done to fix this? Is there anything else that could cause gas consumption to increase 3-fold in a matter of days? I did hit a big pothole the other day but I don't smell any gas, so I don't think there's an external leak. Thanks in advance
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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after driving for a while, you could use an infrared thermometer to check the hub temps, that amount of drag should cause some heat - compare hub temps each with its mate on the other side of the car, more that -what? 30-50* temp difference would be a concern I think. An odd smell might also be a clue. Temps front-to-back might be a little different, but no 100* so, not certain about that.

no reason not to have the all the brakes checked out, pothole may have caused an issue.

is the CEL on? any other work done recently? new tires? any odd pulling or jerking?
 

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No need for infrared thermometer - After driving at highway speeds for awhile... gently feel the temperature of the lugnuts with your fingers. They should be no more than slightly warm.
 

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2008 Outback 2.5i, 2009 Forrester 2.5 sohc
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How much of a drop? 10% or greater? I find in Sept my mileage drops when the stations start selling ethanol fuel
 

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How much of a drop? 10% or greater? I find in Sept my mileage drops when the stations start selling ethanol fuel
Is there anything else that could cause gas consumption to increase 3-fold in a matter of days?
A 3-fold increase in fuel consumption would be a 67% drop in mileage, or, it now takes 30 gallons to travel as far as he used to get with 10 gallons! :gasp:

From the info provided, it sounds like something is dragging. If it's that bad, it should be relatively easy to track down because either something should be getting very hot, or there should be a strong smell of unburned fuel in the exhaust, or both.
 

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2008 Outback 2.5i, 2009 Forrester 2.5 sohc
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606 Posts
I mis read your post, I didnt see the 3 fold decrease. Are you saying you went from around 30 mpg to around 10 mpg? Did you check for a leak in the gas tank?
 

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A failed coolant temp sensor will do this- it'll never go closed loop.

But don't start throwing parts at it yet.
Good suggestion
I would think a failed coolant temp sensor show up as a bad reading on the temperature dial (an OBD2 readout would also let you know if it's giving out bad values). That would be a good indicator. You should see the needle move up as the engine warms up until it is up to operating temperature where it should sit for the rest of the drive (about 1/2 way up).
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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superb suggestion from cnydave,

2 different temp sensors. I for the guage, 1 for the ECU.

they were physically separate in older cars, then they went with 2 sensors in one 'plug' on the crossover pipe.

knock sensor might be a possibility.....
 
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