Error Code P0171 System too Lean (Bank 1) 09 WRX

Discussion in 'General Subaru Discussion' started by MNGman, Nov 8, 2015.

  1. MNGman
    Offline

    MNGman Well-Known Member

    Likes Received:
    377
    Trophy Points:
    248
    So I keep throwing this code. I have narrowed down to when it happens. Usually when at idle (think stop light) I also am experiencing a low/rough idle when I'm at a stop light. I am not noticing any ill effects any other times while driving.
    I have tried replacing the air filter, and cleaned the MAF sensor.
    Just asking if anyone has had experience with this, and which sensor I may need to replace. I'm looking for a little direction before I take the shotgun approach and start replacing parts.
     
  2. EricS
    Offline

    EricS Nooberator

    Likes Received:
    1,061
    Trophy Points:
    348
    vac leak? I've got a boost leak Tester you can borrow if you want, so does sheen and probably a number of folks.
     
  3. Nhibbs
    Offline

    Nhibbs Well-Known Member

    Likes Received:
    2,222
    Trophy Points:
    348
    Easiest way to test vacuum leak is to just spray starter fluid all over your engine bay while the car is running. The vacuum leak will suck up the starter fluid and the idle will smooth out for a bit.
    Make sure the car is really hot and you spray all around the exhaust manifold. Totally safe...just make sure you are up to date on your insurance.
    Otherwise gasoline and a road flare is a proven fix for this type of problem.
     
  4. TMF
    Offline

    TMF Well-Known Member

    Likes Received:
    1,550
    Trophy Points:
    248
    [​IMG]
     
  5. Nhibbs
    Offline

    Nhibbs Well-Known Member

    Likes Received:
    2,222
    Trophy Points:
    348
    Both srs and not srs at the same time. Spraying flammable stuff is a way to test for vacuum leaks and people do it all the time, I just think its a dangerous thing to recommend to any random person on the internet because they will probably start a big fire.
     
    tehfuzz likes this.