The Dreaded Subaru p0011 and p0021 DTC Codes, Don’t Let Them Wreck Your Turbo!

So DO NOT do what we did when our Project GD STI turned on a p0011 OBD DTC code.  What we figured was some sort of sensor issue ended up ruining our beloved Precision Ball Bearing factory upgrade turbo!  Project STI is actually my daughter, Christa’s car and she has been driving it to school every day for the past two years.  One day she told me that she was getting a check engine light and she had checked the code with her Cobb Access Port and it was a p0011.

Looking it up, a p0011 is a variable cam timing error for the left cylinder bank. Knowing that the AVCS sprocket rarely gives trouble we checked the resistance of the cam sensor which was fine, then checked the harness for continuity and a good ground which was also fine.  We scratched our heads and erased the code to see if it would come back.

A few days later it came back and on the same drive, a p0021 code threw as well which is the code for the right cylinder bank. Then the turbo started to make more noise! Oh no! So it was time to do some research.  Apparently these are common codes for the STi and WRX. There was a TSB, or technical service bulletin, issued regarding the filter screens for the AVCS sprockets clogging up. It affects WRX and STi models made before 2006.  This can cause the p0011 and p0021 codes so it was time to check that!

Normally it is pretty easy to check the AVCS sprocket screens.  They are in the banjo bolts to the oil feed line for the AVCS sprockets. However, our car has a Greddy front mount intercooler so we had to remove the charge pipes.

Our car also has Injector Dynamics large fuel rails and the AN fittings for the fuel feed block socket access to the banjo bolts.

We used an open-end wrench and a crescent wrench to undo the banjo bolt like this.  This way we didn’t have to take the fitting off the fuel rail.

The TSB says to discard the screens found inside the banjo bolt.  On our car, the screen was already gone.  Someone must have performed the TSB on it at one time or another.


  1. Had this happen on the family Legacy GT while I was in college. I spent the better part of a month trying to figure this one out. I too thought it was an electrical problem and knew for a fact the TSB was done because my parents bought it new and did all the service at the local dealership. When I got around to looking at the turbo it was too late and we had to get a new one. My commute to campus was also only like 5 miles so I could thankfully catch a bus there while I tracked the problem down.

  2. Mike,
    You might run BG EPR through just before the next oil change and short cycle the oil change (500 mi) after that to clean out the oil passages. The 05-06 (BL/BP) Legacy had a bigger problem with the stock VF40 turbo because the turbine shaft had a very thin center. When the filter would clog the turbo would grenade and send shrapnel to the pan, contaminate the oil cooler and load up the filter until it went into bypass. Finally taking out the engine bearings. Many XTs and GTs met their demise this way. I bought my 05 GT with a new turbo bolted on. I replaced the oil cooler and banjo bolt with the unfiltered AVCS part, cleaned the pan and the oiling system components, as well as changed the oil at three 500 mile intervals with conventional oil (3k thereafter with synthetic). The EJ255 lasted another 60k until the bottom end became too noisy at 200k. It was a good excuse to rebuild it with EJ257 crank & rods, King bearings, and Mahle forged pistons and I rebuilt a VF52 for it

  3. The LH AVCS Filter is located on the front of the cylinder head behind the inner timing cover. You need to disassemble all the timing belt and LH Cam gears to gain access to it. Putting it on top would sure make it easier, but that’s why you didn’t find the filter.

    1. I am pretty sure thats what we got and its the same as pics from other people, the TSB, and youtube videos. When I take in the engine apart I will verify!

    2. See Hammerdown’s post on LegacyGT: this banjo bolt can be removed by filing the nub off the bolt and gently prying the timing cover.

  4. Mike , the banjo with the dimple is typically the one with the screen. Ryan is right about the driver’s side.

  5. This post is pretty old. Hoping someone can help me out. My wife’s 2011 Subaru Touring XT (turbo) is pulling those same codes. P0011 & 0021. Synthetic oil change done 3k miles ago, just did another one today just to be sure it’s clean. Mobile 1 – 5w-30 with top line oil filter.
    Car only has 59k miles. I am trying to find location of the banjo bolts. Only seeing pics & vids for 2010 and under. Anyone know the location? Thanks!!

    1. Might be too late, but banjo bolt one is behind timing cover on driver side. 2 is behind the block passenger side, and 3 is under the intake manifold passenger side. Gotta pull off a ton of stuff to get them all

    1. Shell Rotella T6 5W-40 is the go to oil for our cars. I switched from Mobil 5W-30 and I have noticed less oil loss between changes. Mobil oil is too thin and gets past the turbo seals and gets burned.

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