Check engine codes 1151 & 1152

[snipe2]

Check engine light came on today. Checked the ecm and the codes 1151 and 1152 showed up. Anyone know what they mean?

 

[aldive]

P1151 - Lack of HO2S : A HEGO sensor : See Possible Causes :
: -21 Switch, Sensor : indicating lean at the : for DTC P1130 :
: Indicates Lean : end of a test is :
: : trying to correct for :
: : an over-rich :
: : condition. The test :
: : fails when fuel :
: : control system no :
: : longer detects :
: : switching for a :
: : calibrated amount of :
: : time. :
.
: P1152 - Lack of HO2S : A HEGO sensor : See Possible Causes :
: -21 Switch, Sensor : indicating rich at the : for DTC P1130 :
: Indicates Rich : end of a test is :
: : trying to correct for :
: : an over-lean :
: : condition. The test :
: : fails when the fuel :
: : control system no :
: : longer detects :
: : switching for a :
: : calibrated amount of :

from Dead Link Removed

 

[snipe2]

So can I assume I need to replace the -21? (whatever that is).
Thanks