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Registered
2009 Forester XS Auto
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3 Posts
Discussion Starter · #1 ·
Hi,
  • I bought a 2nd hand Forester XS 2009 12 days ago.
  • Yesterdays (after 11 days) the Engine light and Sliding control light witched on and the Cruise control start flashing.
  • Went to Subaru dealer who told me I have a problem with the catalytic converter problem - P0420.
  • Few hours after these lights went on,the fuel consumption drop by 35%. Was 10.4 KM per Liter and now 7.0 KM per Liter. That is not just a presentation problem, the car actually burn 10 Liters over 70 KM drive! (re-fueled again after that drive)

Please assist urgently, as I have two days left to take the car back to the dealer and get my money back (14 days money back)

Thanks,
OK
 

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2011 Forester X Premium AT
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812 Posts
Did you have a noticeable drop in power? Can you describe more of the problem/symptoms?

One thought: A clogged catalytic converter can severely increase fuel consumption but would also hurt performance. I would expect fixing them would be expensive say over $500.
 

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2009 Forester XS Auto
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3 Posts
Discussion Starter · #3 ·
No Drop in power during my 12 days of driving, nor after the lights whet on.

I have notices that Fuel dial dropping too fast the morning after the lights whet on.
The Fuel consumption calculator start dropping the same night. It dropped from 10.4 KM/L to 7.0 during 5 minutes drive. 0.2 every few seconds...
 

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Premium Member
'19 Forester LTD CVT
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3,248 Posts
Something is causing the car to run rich (too much fuel for the amount of air in the cylinder). A rich condition causes catalytic converters to fail.

Bad o2 sensor (oxygen sensor) or a bad MAF (mass airflow sensor) would be my suspects. Both are relatively cheap repairs in the US, but I would expect them to cost more in Israel. The catalytic converters are expensive to replace in the US. I would expect a $600-$800 cost in the US.
 

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2013 Forester X Automatic
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200 Posts
P0420 is for catalyst efficiency below threshold. The catalyst or the o2 sensor are the most likely problems. It's not a big deal. Have a shop diagnose it and make the necessary repairs. Or return it now.
 

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2015 Impreza 5-Door Sport Auto (CVT)
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2,351 Posts
Don't even play around with this vehicle. Take it back and get your money back and look for something else.

The possibility of having future problems is very probable.
 

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Registered
2009 Forester XS Auto
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3 Posts
Discussion Starter · #7 ·
Thansk you all.
Is that the reason for the drop in fuel consumption or is it the car computer going crazy or is it another issue?
 

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2010 Forester 4eat
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146 Posts
what aftermarket o2 sensors is everyone going with??? there are a couple different bosch P/N's on Amazon(yes I am an amazon shopper)....
 
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