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2003 Forester
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10 Posts
Discussion Starter #1 (Edited)
I replaced the front O2 sensor in my 03 Forester X and I am still getting the P0131 error code. I installed a Lambda sensor and wired it into my existing cable. The wiring was easy, the removal of the factory O2 sensor was not. I put a volt meter on the signal wires and I am reading 2.085 Volts yet I am still getting the low voltage error code. Am I missing something?

The Lambda part number is USOS-4000. I just purchased the Bosch direct OE replacement part# 13469.
When that arrives I will install it and post how it worked.
 

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2003 Forester
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Discussion Starter #2
Try again

Received the Bosch oxygen sensor, part # BS13469. Tried installing it the other day. Got the sensor bolted in but when I went to connect it the connector was slightly different. Frustrated I snipped the leads of of some power resisters and stuck them into the connector and used alligator clips to connect the heater, signal and ground wires. At 2.075 volts I got the error code for high sensor voltage.
Ordered the Denso OE replacement sensor part #234-9015. Received it today but it is pouring out. Will install it soon. Hopefully it will be my last time.
 

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Super Moderator
2007 Forester Sports XT 4EAT
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35,682 Posts
I see you're a new member, so welcome to the forum from Oregon! :biggrin:

The front O2 sensor (Air/Fuel sensor) is critical for correct engine operation. As a rule, it should be replaced with a direct replacement. I bought one from my dealership when I changed the one in my '03X. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2005 Forester
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26 Posts
I've posted on this issue previously, but haven't given the driving symptoms. -
Slight hesitation from stop.
MPGs down.

I'm thinking:Front oxygen (A/F) sensor circuit range/performance problem (low input)because of P0131 read from diagnotics run at Autozone.

New MAF sensor installed per Subaru dealer diagnostics... The CEL was back after 1.8 miles.


richy
 

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2005 Forester
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26 Posts
Thanks for the reply Bobby!
I think it's the same sensor that was replaced last December... :icon_mad:
 

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Super Moderator
2007 Forester Sports XT 4EAT
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Hesitation & lower gas mileage is a good clue, but normally I'd expect to see a P0420 CEL code. That would say you're running too rich... hence the poor fuel fuel mileage. Still... if it's early on, the CAT may still be able to handle the excess richness, but if it goes on too long, you may end up with another problem. :frown:

One other thought. If the MAF sensor corrected your problem when it was replaced, it may be dirty. Have you tried cleaning it? :confused:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2005 Forester
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The Sube garage said MAF, so I purchased a Denso unit off the net and tossed it on myself. Even tried cleaning the original. I tossed the new one in and diconnected the batt for about 10 minutes also.
Took the Forester out for a test and had the light return after 1.8 miles.....or about 10 minutes.

I have an appointment on Monday with another dealer..
 

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Super Moderator
2007 Forester Sports XT 4EAT
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It's sounding more & more like a failing front O2 sensor. Not too expensive if you DIY & I'd recommend a OEM/factory O2 sensor, since this is critical for correct engine operation. Of course having a dealership install anything will add to the overall cost. :icon_eek:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2005 Forester
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I'll probably give the second dealer a shot at it this time. I mean I would do the o2 sensor if they ran diags and gave me the exact part to fix the problem, but I'm afraid of buying part after part to "maybe" fix the issue.
I'm hoping that the "new" dealer can figure the issue out.
I'll ask SOA later about any warranty coverage...if is indeed the same sensor that failed almost 12 months ago (to the day).

Thanks again for your input!

richy
 

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2002 Forester
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293 Posts
Are you sure you used the right sensor? I bought Bosch direct fit ones and replaced both at around 107,000 miles. No rewiring was necessary. That was over a year ago (maybe 2 years ago) and I haven't had the CEL come back.
 

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1999 Forester
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24 Posts
uggGGG!!!

I've recently replaced my front 02 with an oem one and am still getting the dreaded p0130 code....:evilatyou:

Any ideas?

I've reset it by diconnecting the battery 3 times, and had used my code reader/clearer a few times also. Anyone else have a problem with this?

thanks-
Royd
 

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2007 Forester Sports XT 4EAT
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You do know this thread is on a P0131 & not the same as a P0130. :wink:

P0130 - Front oxygen sensor circuit range/performance problem (lean)

This says you're running lean. Assuming the O2 sensor you replaced is good, perhaps the problem is farther up stream. My notes say your '99 is MAF. Have you cleaned the MAF sensor? :confused:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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1999 Forester
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Sorry for Jacking this thread folks. No disrespect intended. :biggrin:

Thanks Bobby, I'll try to clean my MAF tomorrow and let you know how that pans out.
 

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1999 Forester
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24 Posts
Bobby,
You are a genius!!!!:icon_biggrin:

Cleaned out MAF sensor. Car runs much better now!:woohoo:

On a side note, for those that have the 99 I suggest you register with Subaru on their website. I found out that I'll be getting a new MAF sensor free of charge sometime next week.

thanks for the help,

Royd
 

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2007 forester
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29 Posts
How do you take out those clips that hold the o2 sensor wire? I dont want to break it and its hard to tell how they come off
 

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2002 Forester Manual
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Replaced upstream sensor with Denso OEM unit and still getting p0131 code

Hello guys!!

Even though I've been following a lot fo posts here this is my first posts!! Anyway, I have a 2002 forester completely stock 5 speed MT. The check engine started with a P0420 code. I replaced the cat converter and the upstream sensor with a Denso OEM unit and now I ahve the P0131 code. Don't know what to do!!

I checked the connectors and one pin has around 12.5 voltage, other two have around 2.5 and the other two have a resistance of about 5.5 Ohms. I really love my forester but this CEL is getting into my nerves.

Any recommendations will be greatly appreciated

Best Regads
 
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