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subaru forester xt 2012
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8 Posts
Discussion Starter · #1 ·
I have these error codes, help please.

B900 - 083268
U167 - 144623
U422 - 000000
 

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'14 Forester XT Touring
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766 Posts
Are you sure those are the right trouble codes? Because I can't find anything besides one. And only with using U167 number only the other numbers don't show up at all.

U167 Lost Communication With Vehicle Immobilizer Control Module

Most trouble codes start with P
 

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subaru forester xt 2012
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8 Posts
Discussion Starter · #5 ·
so today I got a obd2 scanner and downloaded torque lite, the only code it showed was a p0420, and not any of the 3 codes that came up on the dash. I cleared the p0420 error and now the car seems fine.
Any useful comments would be greatly appreciated.
 

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2010 X Limited, 2.5L NA, 4AT. Purchased as the second owner in 2020 with ~126K miles.
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149 Posts
The OBD code p0420 is a summary code indicating that something was not quite right with the catalytic converter output at some point in the past. The code is not a basis for action except to investigate further.

The other codes of concern in this thread are coming from the 'Body Integrated Unit' and are not accessible with an OBD reader. You'll have to look into the manual for your model year or wait for someone with specific information to know more information about them.
 

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subaru forester xt 2012
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Discussion Starter · #7 ·
after clearing the p0420 yesterday, it came back "P0420 Catalyst System Efficiency Below Threshold Bank 1 "
what do I need to do to fix this?
 

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'14 Forester XT Touring
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@jet screamer
It can be a simple or pricy fix. Usually its a problem with your O2 sensor(s) or a leak somewhere. Not sure if you have two or one for New Zealand modes. Worse case you might need a new cat.
But as a wise old man once told me, if you going to throw money at, start with the cheap stuff first.

So time to get a new O2 sensor. Or figure out how to test it. Yes there is a way to test that. You have to be handy with a multimeter and have the Subaru's repair manual for info. Or...pay some one to do it.
 

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subaru forester xt 2012
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Discussion Starter · #9 ·
Yes bank 1 02 sensor seems like a good place to start, I'll take it out for a bit of a look.
 

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subaru forester xt 2012
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Discussion Starter · #10 ·
So I replaced my downstream 02 sensor soaked my upstream 02 in petrol to clean it and reset the fault code, son of a ***** p0420 came back on after 100k's. So should I buy a upstream 02 sensor? The car is missing a little under load but my fuel economy is still really good. Any suggestions would appreciated.
 

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2011 Subaru Forester
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1,380 Posts
The sensors work in concert. I have always replaced both when doing so as preventative maintenance. With age, they can become marginal even if they aren't setting off a code.
 

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subaru forester xt 2012
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Discussion Starter · #12 ·
So I changed the spark plugs and replaced the K&N filter with a standard filter. I have not had the p0420 error or any other errors come back. I do have a slight hesitation accelerating between 2500- 4000 rpm.
 

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'14 Forester XT Touring
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Good to hear,
Give it time for the ecu to relearn. You can YouTube it, or just do a few wide open throttle runs. It will get better, ecu's are slow to relearn.
 
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