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2002 Subaru Outback Limited Wagon, 2.5L H4
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Discussion Starter #1
Hello! My car has been a bit of an jerk lately. I took it in for a diagnosis, and the guy said first thing I need to do is replace the front O2 sensor and afterwards reprogram the ECU ($342).

I think I could replace the O2 sensor myself pretty easily and save quite a bit of money. My question is do I really need to have my ECU re flashed just because I replaced an O2 sensor? I've been googling about the forums, and no one seems to have even mentioned the idea of reflashing after replacing the O2 sensor.

Any thoughts from you wonderful Subaru folks?
 

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2001 VDC/SC One of a Kind
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I would be interested in knowing why they want to change the AF sensor. What code(s) were pulled from the ECM?

07-60-07R is a tech bulletin stating that all other items/systems that would effect rough idle/running should be checked first before assuming an AF sensor failure. There is nothing in the bulletin concerning a reflash to correct a problem.
 

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2002 Subaru Outback Limited Wagon, 2.5L H4
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Discussion Starter #4
That's so weird. I took it to a reputable Subaru shop and the guy seemed legit. He was so insistent that the problem will not go away until I reflash it.

The codes I'm getting are:

P1137 - front oxygen sensor
P0106 - MAP sensor
P0130 - Running lean
P0172 - Running rich
Plus there are misfire codes for all four cylinders

The guy said they monitored the sensor and it is barely functioning.
 

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2020 Limited
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13 Posts
I can think of no reason why the ECU would have to be reprogrammed. Yes, the trouble codes will need to be cleared but unless the ECU is faulty, no need for reprogramming.

From what you've posted, I'd say, replace the O2 sensor, clear the codes, and see what happens.
 

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2002 Subaru Outback Limited Wagon, 2.5L H4
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Discussion Starter #6
Yea, that seems like sound advice friend. The mechanic just freaked me out a bit. Never heard of anyone "needing" to reflash the ecu for a new o2 sensor before. Thanks very much :D:D:D
 

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Premium Member
2001 VDC/SC One of a Kind
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That's so weird. I took it to a reputable Subaru shop and the guy seemed legit. He was so insistent that the problem will not go away until I reflash it.

The codes I'm getting are:

P1137 - front oxygen sensor
P0106 - MAP sensor
P0130 - Running lean
P0172 - Running rich
Plus there are misfire codes for all four cylinders

The guy said they monitored the sensor and it is barely functioning.
You may want to check the grounds on the engine first or you may have the same problem. A loose or corroded ground will cause these codes to pop up and the car to run bad. All 4 of these are connected to the same problem. The map sensors hardly ever fail. The AF sensor is one tough sob. You have combination codes for rich and lean, which is indicative of a ground or amperage issue. The misfires will be caused by slow or dumb reactions from the ECM due to low amperage also.

Check the ground cable at the battery, and then put you hands on as many ground anchors as you can find and check for looseness and look for corrosion build up.

Had a 2.2 in today that would run fine, then it would shut off like you turned it off and wouldn't restart. Had codes for IAC, both the AF and the rear O2 were reading 0.00, LTFT was way up. I found a loose ground at the intake which is also the ground point for these sensors and IAC along with the ECT and TPS. Cleaned, reattached and the car fired right up and all readings were normal. The spike did make the temp gauge swing around. Spent 30 minutes repairing that without changing parts in the instrument cluster.
 

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2001 VDC/SC One of a Kind
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I don't call them the "stealership" for nothing and the guy you talked to only knows what the tech told him. The tech is most likely incorrect or just trying to bill easy hours.
 

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2002 Subaru Outback Limited Wagon, 2.5L H4
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Discussion Starter #10
Cardoc, do you know how I find out where my ground points are? I put a new ground wire on the battery cable a while back, but I'll make sure it's not corroded. Finding these other ground spots seems a little more difficult.
 

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2001 VDC/SC One of a Kind
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Cardoc, do you know how I find out where my ground points are? I put a new ground wire on the battery cable a while back, but I'll make sure it's not corroded. Finding these other ground spots seems a little more difficult.
Ground anchors are all over the place. You want to concentrate under the hood. There is the main cable from the battery to the block, battery to body, then you have several that run from the block to body, out of the harness to the body or block. Anywhere you see a cable anchored to the block or body, that is a ground source for the sensors and computers. You can also pick up a 4ga cable with eyelets at both ends from the parts store. They are available in many lengths. Attach it between the neg battery post and the block/intake manifold to increase conductivity. (This also helps with you all who have high amp sound systems. Plus, install a larger ground on your amps. You'll be surprised at how much better the amp works.)
 

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2014 OBW 3.6R Limited, 1997 OBW 2.5L Auto (sold, but not forgotten), and 1991 Ford F150
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Snow barrr, I know this is old but the same game is on the table but the stakes are now up to ~$700. 00 after fees and tax. Did you replace a O2 and get the flash? I told the service manager I could not right now cuz I was having a medical emergen=cy when I heard what he wanted to fix the CEL.
 

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On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
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26,134 Posts
Snow barrr, I know this is old but the same game is on the table but the stakes are now up to ~$700. 00 after fees and tax. Did you replace a O2 and get the flash? I told the service manager I could not right now cuz I was having a medical emergen=cy when I heard what he wanted to fix the CEL.

the member in question has not signed in since 2015. (one of the reasons to not dig up a old thread, looking for new answers).

what car do YOU have? (year, model, engine?,...miles?)

how much did they charge you for what they did. ? (did they give you a list of codes / parts?)
 
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