04-06 GT 02 Sensor (Front) Part No.

[JSP]

Not sure if this is the place to post this but thought it might be useful as the 2.0Lt seem to have a known issues with the front 02 sensor.
Part number is 22641-AA220 (late 03-06) & AA390 (04-06)
It's a Denso item which subaru use.
AVO sourced this for me and can confirm that the factory sensor uses a Denso item.
Car now runs normal again.
So if your car has rough idle, then most likely its your Front 02 sensor, and/or injectors.

Jun

[2fast4u]

How many 02 sensors are there.?

These are totally unrelated to AF sensor arnt they?

[Ric]

..
These are totally unrelated to AF sensor arnt they?

I think the AF will be an airflow sensor BEFORE the engine.
The O2 sensor is in the exhaust. I'm not sure if there is one after the exhaust headers meet, or two, one in each header.

[JSP]

THeres one near the Front pipe and there's also a rear one which sits near the 2nd cat i do believe.
The Front one is generally the one that needs replacing, although Subaru recommend replacing both at 160k service.

[2fast4u]

Ok Ive just looked at the Workshop manual for the Gen4 (Its American version of the manual I think but should be the same)

The front oxygen sensor (AF) is located just back from the turbo, infront of the first cat.

Reading the troubleshooting for this sensor they talk about loose connections etc. as being possible causes for the warning lights (logged code ) to come up. Its only after these are checked and proven to be not the problem that they should replace the sensor, according to there procedures to follow.

This is important to me because Subaru had only just been working on my car not 10 minutes before I started getting the code. I had a new key paired to the car.

I wonder how accessible this sensor is. Id like to eyeball this sensor and see if its loose.

If youd like a copy of the Gen 4 manual you can find it in the first post on this page. Its a 130mb download (from memory)

http://www.ozliberty.com/forums/showthread.php?t=1101

Once you have it go to the "engine diagnostics" folder (folder 10) then go to pdf 4 -"Electrical component location". Scroll down to diagram 10.

[2fast4u]

Ive just had a look in the engine bay. At the back left hand corner of the engine cover (near the firewall) I look straight down and there is a senor pointing up with a yellow cable coming off of it .

If that is it. It appears to be an easy accessible location. Subaru quoted me $400 for the part and a further $200 to fit it.

[JSP]

Where abouts are you located?
If you're in Melbourne give AVO a call, they just fixed my car last week which had very rough idle and really bad fuel economy issues.. This was due to the FRONT 02 Sensor.

[2fast4u]

Where abouts are you located?
If you're in Melbourne give AVO a call, they just fixed my car last week which had very rough idle and really bad fuel economy issues.. This was due to the FRONT 02 Sensor.

Im in Brisbane. I dont have rough idle or bad economy. I do have a code that has pointed to my front 02 (AF) sensor tho.

I really think this is a very straight forward job to replace. Access is actually not to bad ,Subaru want to charge $200 for fitting it though

[tangcla]

I've had mine replaced three times - fortunately I only paid once ($450 or $550 fitted)

They also say something about the ECU needing to be reflashed after fitting it...? Not sure what exactly that encompasses.

[jdm rsk]

I've had mine replaced three times - fortunately I only paid once ($450 or $550 fitted)

They also say something about the ECU needing to be reflashed after fitting it...? Not sure what exactly that encompasses.

go after market bosch half the price fitted

[suff]

you can get "generics" from ebay for ~$100.. fit it yourself, they are a push plug and both the upper and lower sensors are easy to access.. just look for the bright yellow cable sheilds (upper one is to the left on the rhs of the exhaust, just behind the TMIC, lower one is near your gear shit (if a manual)

Highly recommened resetting your ECU though, as if your O2 sensors where stuffed, you will be giving our ECU a heck of a suprise when it starts getting "correct" information on the O2 sensors

[2fast4u]

you can get "generics" from ebay for ~$100.. fit it yourself, they are a push plug and both the upper and lower sensors are easy to access.. just look for the bright yellow cable sheilds (upper one is to the left on the rhs of the exhaust, just behind the TMIC, lower one is near your gear shit (if a manual)

Highly recommened resetting your ECU though, as if your O2 sensors where stuffed, you will be giving our ECU a heck of a suprise when it starts getting "correct" information on the O2 sensors

Yeah I can clearly see the sensor and it looks relatively easy to work on. It plugs into the loom at the top (Under the TMIC) and is screwed in to the exhaust at the bottom.

In the past Ive reset my ECU by dissconnecting the battery (Gen2 GT). Is this still the case for the Gen4. Leave it disconnected overnight?

Can you (or anyone else) point me to where to find these on Ebay. I type in 02 sensor and get virtually no results. Nothing related to Liberty at least. Although I did see someone selling them a few weeks back (before I knew I needed one)

[suff]

yup, DC your battery for a few hours.. and then drive it like you stole it when you connect it all back up.

This guy carries the Subaru compatible 4 wire sensors

http://cgi.ebay.com.au/OXYGEN-SENSOR-O2-SENSOR-4-WIRE-UNIVERSAL_W0QQitemZ140299622330QQcmdZViewItemQQptZAU_Car_Parts_Accessories

[2fast4u]

yup, DC your battery for a few hours.. and then drive it like you stole it when you connect it all back up.

This guy carries the Subaru compatible 4 wire sensors

http://cgi.ebay.com.au/OXYGEN-SENSOR-O2-SENSOR-4-WIRE-UNIVERSAL_W0QQitemZ140299622330QQcmdZViewItemQQptZAU_Car_Parts_Accessories

Is that the front 02 (AF) sensor near the turbo.