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Old 11-24-2010, 11:28 AM   #1
ScottyDaug
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Default Help - Replacing O2 Sensor in 05 - RS 2.5

Hi,

I have a 05 Impreza RS. The CEL came on. I checked the code, and it came back P0131 Sensor Circuit Low Volts (Bank 1 Sensor 1). After doing a little research it sounds like this is a bad, or going bad O2 Sensor. Is Bank 1 the sensor in front of the cat? I would like to do this myself. Does any one know the step by step procedure, or a link to some instructions? I would greatly appreciate any help with this.

Thanks In Advance,

Scott
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Old 11-24-2010, 11:50 AM   #2
Samirr76
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Its pretty easy as long as you can reach it, you would need ramps or a lift typically. Also, an O2 socket wrench is recommended. Its just like replacing a spark plug.
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Old 11-26-2010, 12:32 AM   #3
PULMEOVR
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Just don`t go to the dealer ... $641 CAD is what I paid (stupid me)! OUCH!
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Old 11-26-2010, 02:30 AM   #4
williaty
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1) ABSOLUTELY buy a DENSO brand O2 sensor. For whatever reason, the 05 RS chews up and spits out Bosch sensor like they're cheap tobacco. I have no idea what's different about the 05 (and it does seem to be only the 05) but they don't really get along with anything other than the Densos.

2) You'll need a 22mm O2 sensor wrench if you still have the stock heat shields on your cats. If you've removed the heat shields, you can use any random 22mm open end or box wrench in addition to the O2 sensor socket.
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Old 11-29-2010, 12:15 AM   #5
DJBybee
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DIY tip for finding out which sensor is which (especially helpful for systems with 4 or 5 or 6 sensors):

Unplug them one at a time, restart the car and check codes again. The code you generate with an unplugged sensor will probably be for "signal absent" but it will let you know which sensor is which.

Denso sensor or OE.
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Old 11-29-2010, 12:16 AM   #6
williaty
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... Why the hell would you need to do that?

The DTC itself tells you which O2 sensor is bad.
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Old 11-29-2010, 09:03 PM   #7
DJBybee
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Responding to : "is that the one in front of the cat?"

My last experience was on an 04 Outback that has 5 oxygen sensors. Bank one, bank two, sensors #1, #2, #3.
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Old 11-30-2010, 01:19 AM   #8
sc00ter
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I had to replace the front 02 sensor on my 05 RS 3 times in 80k miles. P0131 was the code that was thrown every time it needed to be replaced. Average cost was $200 believe. I wish I would have known about the Denso sensors in the 05's.

Listen to williaty. He knows his stuff.
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Old 11-30-2010, 01:21 AM   #9
williaty
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Yup, your postings, my experiences, and a couple of other guys are what convinced me that the 05 is doing something weird with the sensor that kills anything other than a Denso.
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Old 11-30-2010, 02:06 PM   #10
formula91
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Quote:
Originally Posted by williaty View Post
Yup, your postings, my experiences, and a couple of other guys are what convinced me that the 05 is doing something weird with the sensor that kills anything other than a Denso.
Correct me if I am wrong, but OEM is denso. Can't go wrong with OEM.
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Old 11-30-2010, 02:42 PM   #11
colorfull
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Ah the 2005 Impreza...
Changed my sensor 4 months ago (got a Denso unit), and my car is throwing a code again after 10K miles...
Last one came out soothy black, could it be that the 05 runs too rich and the sooth kills them?
Granted, I have a TWE header, and my code is 2096, different of the OP. But still?



Quote:
Originally Posted by williaty View Post
Yup, your postings, my experiences, and a couple of other guys are what convinced me that the 05 is doing something weird with the sensor that kills anything other than a Denso.
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Old 11-30-2010, 03:35 PM   #12
williaty
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You would need to run RICH, like richer than 10, to kill a sensor. Something is definitely amiss, though.
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Old 11-30-2010, 04:06 PM   #13
formula91
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Quote:
Originally Posted by colorfull View Post
Ah the 2005 Impreza...
Changed my sensor 4 months ago (got a Denso unit), and my car is throwing a code again after 10K miles...
Last one came out soothy black, could it be that the 05 runs too rich and the sooth kills them?
Granted, I have a TWE header, and my code is 2096, different of the OP. But still?
According to the parts catalog, the 05 RS uses a different O2 sensor than the other years before and after. Go figure, considering we're the retarded/transition year.

I'm not sure why it's assigned a different part number, or what the differences are, but they are different in the parts catalog.

I also borked an O2 sensor at around 30k miles. At this point in time, I have a strange suspicion that the o2 sensor is starting to go bad again. I get lots of fuel vapor smoke out the tailpipe after autox runs. I think it's starting to go towards rich again.

Check anything that has to do with AFR. I'd probably check the MAF first.
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Old 12-07-2010, 03:23 PM   #14
Gr3en
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I just replaced my front for a third time and I used a Denso. Got the PN from the denso website and ordered it from NAPA. Kinda pricey but I need my car to run for DD uses.
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Old 12-07-2010, 04:41 PM   #15
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Whatever you do DONT buy the splice it yourself sensor LOL. 05's may kill sensors faster due to particulate build due to catalyst substrate deterioration upstream?? Two cats before the rear sensor just a guess.

The dealer put a whole new manifold on my 2008 legacy when I got a similar code and reused the sensors and i havent gotten that since (that was 40K miles ago)
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Old 04-17-2014, 07:48 PM   #16
CR7_2011
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Does anyone have a specific part number to replace the 02 sensor from rockauto? I am getting conflicted between part #2349011 and #2349015. Which one is it? I have read different things on the forums and I am confused an not sure which one is the correct part. They almost look identical.
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Old 04-18-2014, 05:06 AM   #17
EdHilario
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2349122 is the front O2
2344732 is the rear O2
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Old 04-19-2014, 05:48 PM   #18
CR7_2011
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Now you give me another two part numbers. So i have now got 4 part numbers from this website for the same code... Even more confused now...
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Old 04-19-2014, 07:09 PM   #19
EdHilario
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Which sensor are you replacing? There is FRONT O2 and a REAR O2.
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Old 04-23-2014, 07:52 PM   #20
CR7_2011
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I have both these ECL codes on a Subaru Impreza 2005:

p0131 (O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
p0031 (Heater control circuit (Bank 1 sensor 1)

I think it's the front sensor based on those codes right?

I'm just really hoping to find out the correct part number in order to replace the sensor that is giving off these codes. It's too hard to order the part until I am able to confirm the part number.

I have done lots and lots of reading on this forum and it looks like rockauto is the best place to purchase a sensor. However, I have come across two different part numbers on this forum in different threads relating to these codes and replacing the O2 sensor, which is why i am confused about which one to get.

# 2349011 http://www.rockauto.com/catalog/cata...ENSO%2B2349011
and
# 2349015 http://www.rockauto.com/dbphp/x,cata..._2349015.html0

Do I need to replace both sensors? Or will replacing one of these fix the other code at the same time also, considering that the codes are both coming from sensor 1 bank 1. Please help to clarify my confusion and point me in the right direction. I just need to know which one it is that I need to get. Thanks.
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Old 04-27-2014, 11:27 PM   #21
EdHilario
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Replace the front sensor.
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Old 04-28-2014, 08:48 AM   #22
Subie-Lifer
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Dude just buy the denso upstream and put it in. It's probably an air/fuel ratio sensor. More $$$. Who ever had 5 sensors must have missed something cause it doesn't.

Also a 7/8's wrench is all you should need. The connector on your new part should help identify the o2 in question if they are both in the front. I love that wrap around exhaust. burn burn burn
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Old 05-02-2014, 06:14 PM   #23
Uptow4fred
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I paid for a new 02sensor at Subaru a orange colored wire denso and it fixed both codes on the car also had seeburgs show me which needed done
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Old 05-02-2014, 08:02 PM   #24
williaty
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Use only Denso or OEM or you're just wasting time and money because the others will soon fail again. OEM is stupidly expensive but Denso is pretty cheap on Amazon.

Yes, some of them actually have 5 O2 sensors. The only place in the world that gets them is California. I didn't believe it either until a guy from out there sent me a page from their Service Manual.
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Old 05-02-2014, 09:34 PM   #25
skramguts
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by 'front' sensor, do you mean first in line on the header?
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