There was a huge thread if I remember correctly over on NASIOC about this...something with the oil charge valve or the timing belt I believe...However if it was a timing belt problem your car would either not be running or it would def. not be running the way "it always has"... I have seen those tiny filters in the OCV and the ones in the banjo bolt for the turbo oil feed lin throw this code for they get all coked up....

 

Thanks for the reply. I guess I should bring it in to the dealer................

 

Well I can say this code can somewhat be a PITA to track down if it isnt the actual OCV itself...Just like the infamous P0440...Ive seen this code thrown from a burnt valve to a torn vacuum line.....What I would prob do if I where you is first...check the oil level and condition...next I would do an oil change and an engine flush (warm solution that runs through your engine to clean out sludge deposits and such)...after doing these I would clear the code and see if it comes back...What weight oil are you using?

 

Thanks for the reply. I am using 5W-30 Synthetic. I brought it to Subaru and they could not find anything wrong with it. $57 bucks for nothing

They reset it and then the manager asked me to bring it in right away if it happens again. It will and I will be out another 50 bucks

 

It might be worth it for you to buy an inexpensive OBD II scanner so that way whenever the light comes on you will know what the code is before you bring it to the dealer ( if there is even a need to do so ).. ...Speak of the devil I had one today on an 05 Outback P0026....LOF and engine flush and away it went...for now...

 

i have the same problem...car runs great too...Did you end up seeing if the code came back on? after you reset it?

 

I bought a 2006 WRX a few weeks ago and it showed a P0021 today for the first time. Mine is also running fine... Did anyone have luck replacing the solenoid? The guy I bought the wrx from just replaced the timing belt a couple thousand miles ago, so I don't think it's something with the belt.

 

bumping this. what was the culprit? I got the p0021 code tonight as well. car also runs fine. 80,000km completely stock. checked the oil and its perfect level.

 

I know this is an old thread, but did you figure it out, im having this code in my 2016 wrx 96000km, replaces solinoid cleaned the connectors, and did an oil change, and still having this code and a rough idle(only sometimes though)