P1086 & P0031 after pulling/replacing motor. Halp?!

Discussion in 'Modifications And Maintenance' started by Krazylegz1485, Jul 9, 2017.

  1. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Greetings everybody. So, just had the motor out for some maintenance things this last week or so and drove it for the first time again this afternoon. While there were several small victories, of course it didn't go off without a hitch. I've got 2 CEL's now and would like some opinion sharing from the more experienced. Thanks ahead of time!

    03 WRX

    Issues: P1086 (TGV related) & P0031 (upstream 02 related).

    "Changes" made while motor was out:
    -replaced valve cover gaskets, all 4 cam seals and the crank seal, oil pressure sender, PCV valve, and oil cooler o-ring.
    -changed spark plugs
    -put in Tomei uel headers (re-used existing 02 sensor)
    -swapped motor & tranny mounts

    Upon googling both issues, I have a feeling that the P0031 code could be caused by some iffy wiring at the 02 sesnsor itself. I noticed at least one had some of the shielding rubber broken. I wrapped them with electrical tape before installation to prevent it from getting worse. Perhaps I should pull it back out either fix it or replace. Luckily it's pretty easy to access at the right front wheel well.

    Other pertinent information in this area would be that I'm totally catless. Did the resistor mod for the front, and the mechanical "spacer" mod for the rear. Apparently that might not affect this current issue, but just wanted to put it out there.

    For the P1086, I'm not sure. Do the TGV sensors just randomly go bad? I didn't remove anything in this area that I'm aware of. Seems like everything is plugged back in. Only sensor that I messed with was the cam position sensor for the driver side intake came (on the top of that head) while replacing valve cover gaskets and cam seals. Ideally I'll do TGV deletes in the future but that's a little out of the budget for the time being (thinking I'd like to do Aluminati's).

    Much appreciation to anybody offering assistance!
     
    Last edited: Jul 9, 2017
  2. tangledupinblu
    Offline

    tangledupinblu Event Coordinator Staff Member

    Likes Received:
    4,850
    Trophy Points:
    473
    I am wondering if the new headers are causing issues with the O2 sensor?
     
  3. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    That's definitely a possibility, of course. The CEL came on immediately when I started the car, so in my head I was leaning towards a sensor failure I guess. If it's basically a temp sensor would it take "longer" to calculate an issue?
     
  4. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    Check the o2 sensor itself and see if you bumped it when pulling or installing the engine. Look at the sensor end and the wires to the sensor. Would most likely just need a new sensor.

    The tgv one same thing. Just check the sensor and the connection. If they look good may be time to just delete them.
     
    Krazylegz1485 likes this.
  5. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Thanks, Jesse. Really looking forward to the day this thing gets over to your place for a tune. TGV deletes, injectors, more fuel, and a tune is definitely next on the menu.
     
    tangledupinblu likes this.
  6. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Just pulled the 02 sensor out because I couldn't go to sleep tonight without at least checking. Somehow the white wire right up next to the connector got smashed at some point (probably while laying on the floor while attached to the old exhaust) and had a pretty good amount of separated wires.

    Also ohm'd out the black wires and didn't even get a reading. So unwrapped my electrical tape wrap and found another almost complete break or two.

    Guess I'll be checking into a new sensor then. At least I feel like I've got a definitive answer for this one.
     
    tangledupinblu likes this.
  7. JasonoJordan
    Offline

    JasonoJordan Well-Known Member

    Likes Received:
    1,109
    Trophy Points:
    248
    Is the break far enough back to solder and heat shrink?
     
  8. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    That's the best part. Both of them are about a 1/4" from either end. Don't think there's enough room to cut, strip, & splice. Probably gonna give it a shot anyways, since I've got nothing to lose at this point.
     
  9. JasonoJordan
    Offline

    JasonoJordan Well-Known Member

    Likes Received:
    1,109
    Trophy Points:
    248
    Rockauto had some pretty good prices on O2 sensors last time I looked.
     
  10. joebush44
    Offline

    joebush44 Well-Known Member

    Likes Received:
    664
    Trophy Points:
    198
    If the sensor is in when pulling or dropping the motor in, it's fairly easy to bang/scrape it against the frame rail. Or so I've been told :unsure:
     
    Krazylegz1485 likes this.
  11. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    It was in when pulled, and I'm assuming that had a little to do with it. I actually had to "adjust" the sheet metal down there to get it into the hole in the headers once the motor was back in.
     
  12. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Struck out on a quick search for a used sensor locally so scored a new one on eBay for $71 shipped. Hopefully will be here by this weekend.

    So, assuming that takes care of my O2 light, anybody got that magic solution for the tgv one?
     
  13. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    Just so you know, aftermarket sensors tend to have a much higher failure rate. Even the store bought denso ones. We only install the oem Subaru boxed ones for this reason. Less headaches.
     
  14. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    I read that on a handful of forum posts. The one I got is Denso brand.

    http://www.ebay.com/itm/142440014869

    *Just reread your part about the Denso ones. Dammit. Isn't Denso the OEM ones?
     
  15. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    Denso does make the oem ones but for whatever reason we see a higher failure rate with the denso ones over the oem ones. Call me crazy, can't explain it but just what we have seen.
     
  16. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Any idea what Subaru charges for the OEM-oem sensors? Mine came today and the wiring is significantly shorter. Haven't tried it in the car yet but I'm pretty sure I can tell by looking that it's gonna be too short. Sure I can just extend all the wires, but trying to weigh my options here.

    Thanks!
     
  17. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    $220-$250 retail. Mnsubaru has a discount
     
  18. joebush44
    Offline

    joebush44 Well-Known Member

    Likes Received:
    664
    Trophy Points:
    198
  19. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Mine calls for 234-9011. Not sure what the differences are. I also made mine "fit" by just rerouting the car side harness.

    Cool thing now is my 0031 code went away and was replaced with an 1130 (open circuit). So I got that going for me, which is nice.
     
    joebush44 likes this.
  20. joebush44
    Offline

    joebush44 Well-Known Member

    Likes Received:
    664
    Trophy Points:
    198
    Oops - the one I linked to is for GD STi. I realize now that you already got the Denso sensor...odd that the harness was too short. Bummer that you have a different code now. I've had good luck using the "non-oem" Denso sensors, but your car seems like it might be a bit more picky.
     
  21. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Yeah, I'm not really sure what do to now. I've got a basic scan tool and can read and clear codes, but haven't officially "reset" the ecm. That said, I did find the fuse that applies to the O2 sensor circuit and pulled that. Of course it fell underneath the battery as I pulled it out, so have no choice but to remove the battery to get to it, so guess I'll get my hard reset at the same time.

    If that doesn't work, what else? An "open" circuit tells me that the sensor must be dead out of the box, right? Previous code was just "low" which means it either was reading wrong because of the header change or possibly due to the damaged wires causing a big enough change in resistance or something.

    Would love to go drop $200 at Subaru for an actual oem one, but that's gonna have to wait about a month until after we close on the house.
     
  22. joebush44
    Offline

    joebush44 Well-Known Member

    Likes Received:
    664
    Trophy Points:
    198
  23. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    Also if your ecu sees that problem with the o2 sensor long enough, it will cut power to the o2 sensor from the ecu. That could be the "open" circuit problem. Try hard resetting it, if it persists then you got another issue.
     
    Krazylegz1485 likes this.
  24. tangledupinblu
    Offline

    tangledupinblu Event Coordinator Staff Member

    Likes Received:
    4,850
    Trophy Points:
    473
    "Don't argue with me on this one sonny...go get the OEM one"-Unabomber

    lol
     
    silver03 likes this.
  25. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Hahahaha. Saw that one this morning, too.
     
  26. joebush44
    Offline

    joebush44 Well-Known Member

    Likes Received:
    664
    Trophy Points:
    198
    Basically lol
     
  27. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Pulled the battery to get my damn fuse back from the depths. Fuse was fine, put it back in. Reconnected battery and checked the codes right away. TGV code was still there but O2 sensor one was gone. I was stoked. Took it for a trip "around the block" to get everything warmed up and see what happens. Drove fine (still), nothing exciting either way. Got back, read the codes, O2 sensor code came back (1130).

    F'k you, car...
     
  28. pillboy
    Offline

    pillboy Well-Known Member

    Likes Received:
    1,344
    Trophy Points:
    248
    Cars can tell when you are stoked. Never let on. Always expect the worst from the car and you will never be disappointed.
     
  29. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Kinda the opposite, too. When you're sick of them and tell them out loud that they'll be replaced soon if they don't shape up, sh!t just magically starts working right... Maybe I should try some reverse psychology on her.

    By the way, anybody know how to tell wire colors in the Subaru FSM? Looking up the troubleshooting procedure for the specific codes and everything is just black with no color descriptors.
     
  30. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    Copied and pasted here to keep it in this thread.

    Assuming #2 is the big yellow/red wire, I had 12.16 with the key on.

    1 has 2.85, 2 has 12.16, 3 & 4 both have 3.83.

    Commence head into wall...:banghead:
     

Share This Page