Code help

[sxyxc]

ok so i just pulled up a couple codes of my car becuase its cel light was on this is that i got..
P1151 Lack of H02S-21 switch, sensor indicates lean and P1131 lack of H02s-11 switch, sensor indicates lean...

I havn't touched my O2 sensors all i have done is hit them as with my bolts with some PB blaster to make them easy to get off... what could be causing this?? and for both of them to read this?? what gives??

 

[Jrgunn5150]

An air leak behind the MAF can do it, or if they are loose in the mid-pipe.

 

[sxyxc]

i think that they might be loose because i have been giving them some PB to help when i get my new mid pipe...

 

[sxyxc]

new problem!!! ok now its reading my pass side bank 1 O2 sensor has low voltage and running car lean.. it switches between that and the P1151 Lack of H02S-21 switch, sensor indicates lean code, i reset them and then in about 15-20 miles it comes on again.. also i know that this is really bad, but i drive this car ALOT even with the error codes, i kept reseting i drove around 120 miles today.. in city, stop and go, and stuff.. i need this fixed..

also what would be ways to get better MPG mine is really bad, and worste now with this problem... i normaly get about 14-15 on a stock mustang gt vert auto...