CEL on. running lean, o2 sensors dead??

hey ive had my 2002 neon for a while now.. and ive got some parts onto it... recently my check engine light starting coming on... first code was catalyst low efficiency, i have a magnaflow hiflow cat, but the o2 sensor that used to be right in the stock cat.. is now in my downpipe just before the cat.. and the first o2 sensor is in collector of the header...
my CEL is now posting fuel trim system lean bank 1 and catalyst low efficiency, im also going thru a lot more gas then i used to... my A/F meter is also all over the place, and i have it hooked to my upper o2, any suggestions on what i should do to get my car running a bit better.... i thinking fuel filter could be junk... ran on very low amounts of fuel for about a month....( :( no job then,) any questions just email me or reply back... i need to figure out whats going on with my neon... if i need to move the lower o2 to just past the cat... or if they might need replacing... and what i should do about the fuel system...

hey ive had my 2002 neon for a while now.. and ive got some parts onto it... recently my check engine light starting coming on... first code was catalyst low efficiency, i have a magnaflow hiflow cat, but the o2 sensor that used to be right in the stock cat.. is now in my downpipe just before the cat.. and the first o2 sensor is in collector of the header...
my CEL is now posting fuel trim system lean bank 1 and catalyst low efficiency, im also going thru a lot more gas then i used to... my A/F meter is also all over the place, and i have it hooked to my upper o2, any suggestions on what i should do to get my car running a bit better.... i thinking fuel filter could be junk... ran on very low amounts of fuel for about a month....( :( no job then,) any questions just email me or reply back... i need to figure out whats going on with my neon... if i need to move the lower o2 to just past the cat... or if they might need replacing... and what i should do about the fuel system...


yes you will have to move the o2 "downstream" after the cat if the pcm doe not read a significant cahnge in o2 readings from primary vary 200-800mv to the secondary then it sets the code of ineffecient cat then clear the fuel trim readings and go drive to reset everything. would be better if i had the readings from pre cat o2 and aft cat o2 but thats all i can tell from what i have good luck