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Old 08-31-2019, 02:53 PM   #1
Theclerk95
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2001 legacy b4

Default Legacy B4 Code 23 - new maf not helping

Hi I have a 2001 Legacy B4 rev c auto. I am running a fmic, apexi intake, zerosports hardpipe, full decat, dw65c fuel pump, gfb recirc, and am dyno tuned.


Am having some issues diagnosing my issues after receiving a code 23 for the MAF.


I took the car to the dragstrip at the beginning of August and the first run out the car bogged down really bad and it boosted but felt like it wasn't getting any power. The car did switch over to secondary as well and at the right rpm's. It didn't throw any CEL's but after looking everything over and tightening my piping clamps, the second run was no better and the issue was still there with no CEL. Decided to plug in my connectors and the car had a code 23 for the MAF sensor.


Forward to last week and my local dealer finally got an oem MAF in for me, I installed it and the car didn't feel much better and after less than 100km the issues were back and the code 23 was back (again no CEL).


Had the dealer test the MAF to make sure it was getting enough voltage and was reading correctly, and they confirmed it was, and the looked at my o2 sensor voltage as I noticed after logging it it was a bit off.


The o2 sensor at idle was jumping all over from 20mv up to 800mv down to 0mv and up 700mv... well you get the point. They confirmed the same, so I am going to replace the o2 Tuesday as I have a new universal Bosch at home.



Just wondering if anyone else may have some insight on this issue, because if this o2 isn't the issue then I am not sure what to look for next. I had issues with the o2 before and it through a code 23 for that but it also had the code 32 which is for the o2 sensor when it did.


Any help is appreciated thanks!
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Old 09-03-2019, 05:32 PM   #2
Fozymandias
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Had something similar and it was the O2 sensor even though I got a MAF fault code. Unplug the O2 sensor and take it for a drive to check it.
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Old 09-13-2019, 11:40 AM   #3
Theclerk95
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Quote:
Originally Posted by Fozymandias View Post
Had something similar and it was the O2 sensor even though I got a MAF fault code. Unplug the O2 sensor and take it for a drive to check it.
So I ended up replacing the o2 sensor to see if that helped. Car started getting sluggish again after it relearned the parameters. again no CEL but the code for the MAF was back again. I can't hear any leaks while driving, but I'm taking it Monday to get smoke tested. So hopefully that solves it
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Old 09-13-2019, 04:11 PM   #4
Fozymandias
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Did you take it for a drive with theO2 plugged out?

Also, did you use an OEM O2 replacement? I tried a Bosch and a Denso - both brand new OEM replacements but my car didnít like either for more than a day or two. Stumped up for an oem and was perfect after. Should have saved myself Ä100 and just bought the OEM straight off.

I really really really suggest unplugging the O2 and taking it for a drive before buying anything else
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Old 09-14-2019, 10:29 AM   #5
Theclerk95
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Quote:
Originally Posted by Fozymandias View Post
Did you take it for a drive with theO2 plugged out?

Also, did you use an OEM O2 replacement? I tried a Bosch and a Denso - both brand new OEM replacements but my car didnít like either for more than a day or two. Stumped up for an oem and was perfect after. Should have saved myself Ä100 and just bought the OEM straight off.

I really really really suggest unplugging the O2 and taking it for a drive before buying anything else
haven't tried driving it unplugged, but the OEM one that was in the manifold was a bosch o2 sensor, and unfortunately my Dealership can't get an exact oem one, so I just used a universal bosch. Gonna give a smoke test a try and figure if there are any leaks found then that is most likely the culprit
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Old 09-15-2019, 06:52 AM   #6
Fozymandias
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Dude, seriously - it takes like 3 seconds to unplug the O2 and costs zero dollars. I donít understand why you wonít just unplug it and take it for a 10 min drive. It will tell you straight away if itís the universal sensor (which the cars often donít like)
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Old 09-15-2019, 06:09 PM   #7
subaru_gc8
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Quote:
Originally Posted by Theclerk95 View Post
haven't tried driving it unplugged, but the OEM one that was in the manifold was a bosch o2 sensor, and unfortunately my Dealership can't get an exact oem one, so I just used a universal bosch. Gonna give a smoke test a try and figure if there are any leaks found then that is most likely the culprit
ooo german and japanese parts and cars don't play nice together
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Old 09-17-2019, 06:47 PM   #8
Theclerk95
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Well I really don't believe the universal o2 is the issue considering it did it with the oem one in and the OEM one in the manifold was a Bosch as well.

Went ahead and had a smoke test down and immediately the oil catch can I had (cheap d1spec) started leaking smoke out of every seam pretty well. Seems the rubber orings had rotted and the gaskets on the can weren't doing their job either. Had a new can at home so installed that and will see if that helps
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Old 09-19-2019, 07:29 AM   #9
Theclerk95
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Well the leaking catch can was not issue either. Being dropped off at the shop until they can figure it out
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