SES code help

[redfox3369]

SES light has been on for quite some time. It first only had the O2 sensor code to which i replaced the front O2 sensor. The SES light never went off and has been on for about 1 yr or so. The other day i was driving on the interstate and the SES light started blinking at me. So i went back and had the codes read again and i have 2 codes stored: P0131 & P0137, which show Heated O2 sensor bank 1 and 2. Do i need to change out both O2 sensors or does someone know another reason why these errors display? Any input would be greatly appreciated.

[dewaynep]

Those codes are for low voltage coming out of the oxygen sensors. You could just change the sensors and it MAY fix your problem or, you could get it on an engine capable scanner and see what the o2 sensors are doing. You could, while watching the o2 sensor datastream, inject some propane into the intake and see if you see the voltage spike to rich, then you could introduce a vacuum leak that should cause them to go lean. Then, if you see they are working properly you could find out what the real problem is. In other words, the codes don't tell you to replace anything they just lead you to the real problem. It is also possible the reference voltage is too low caused by a poor connection. There are many possibilities, only one correct answer.