Hey i have a 2002 eclipse GS 5 speed, and it threw a code at me and i just cant figure this car out..the code is PO171 which is the car running lean, and i dont know if its my o2 sensor cuz my car has 102k on it or if its a vacume leak, or a MAF being messed up cuz i put a k and n filter.......please help me out with thiss if anyone knows anything please give me a text or email ilb2fast4u@aol.com or 513 393 2799 or post here what ever is easierthank you

 

did it go on right after you put the filter on? if so, try unplugging the battery for about 10 minutes then plug it back in and drive around a little bit

 

How does the car run at idle? If you have a vacuum leak it willhave a rough idle. As long as the intake hose is sealed and the car idles fine I would try replacing the o2 sensor.