My 2011 Forester is approaching 150k miles and I thought I would summarize my experience with maintenance after 90k miles:
P0171 error
The low fuel/air mixture error is a symptom that commonly comes up on older cars and it's due to carbon dirt in the intake. Start by cleaning the MAF sensor, the throttle body, and checking for air leaks. The critical area of the throttle body is where the plate meets the throat of the intake.
Parts not in the manual that contribute to dirty intakes are the PCV and EGR valves. The PCV valve screws into the engine and has a tube that comes up to the intake after the throttle body. Get a replacement riser tube as yours will be brittle and break. The PCV valve is cheap, so get a new one if you like. Remove the EGR valve and spray clean it.
Subaru used to sell an intake cleaner kit, but now you can't find it, so buy an intake cleaner kit from a third party. It comes in an aerosol can with a hose and adapter to plug into a rubber hose. What is really needed is an adapter to plug into a metal port, but if you have some spare hose the size of the PCV riser tube, use that. I used the PCV hose. I was able to spray the entire can into the intake without stalling the engine but I did get some bucking, so I backed off when that happened. I've only used this once recently, so I can't say how often to use it, but I'm thinking 15-30 kmi.
I find the Subaru lug nuts to be easy to cross-thread, so check your tire installer after they do work on your tires. I have a telescoping lug wrench that makes checking easy. If you do get a bunged-up stud, you can remove the caliper and disc rotor and replace the stud yourself. But exercise extra caution as your car ages and the threads on the end of the bolt undergo gradual damage.
That's it! Post additional advice as you see fit. Hope this helps you.
P0171 error
The low fuel/air mixture error is a symptom that commonly comes up on older cars and it's due to carbon dirt in the intake. Start by cleaning the MAF sensor, the throttle body, and checking for air leaks. The critical area of the throttle body is where the plate meets the throat of the intake.
Parts not in the manual that contribute to dirty intakes are the PCV and EGR valves. The PCV valve screws into the engine and has a tube that comes up to the intake after the throttle body. Get a replacement riser tube as yours will be brittle and break. The PCV valve is cheap, so get a new one if you like. Remove the EGR valve and spray clean it.
Subaru used to sell an intake cleaner kit, but now you can't find it, so buy an intake cleaner kit from a third party. It comes in an aerosol can with a hose and adapter to plug into a rubber hose. What is really needed is an adapter to plug into a metal port, but if you have some spare hose the size of the PCV riser tube, use that. I used the PCV hose. I was able to spray the entire can into the intake without stalling the engine but I did get some bucking, so I backed off when that happened. I've only used this once recently, so I can't say how often to use it, but I'm thinking 15-30 kmi.
I find the Subaru lug nuts to be easy to cross-thread, so check your tire installer after they do work on your tires. I have a telescoping lug wrench that makes checking easy. If you do get a bunged-up stud, you can remove the caliper and disc rotor and replace the stud yourself. But exercise extra caution as your car ages and the threads on the end of the bolt undergo gradual damage.
That's it! Post additional advice as you see fit. Hope this helps you.
