P0037 code need help!

Hey guys i have been having a check engine light for a month and decided to check it out is says its p0037. I have been noticing a 4-5mpg loss too. I know its something with the 02 sensors but which one there are 2 on my 2tr fe, the 4cylinder model with 4wd and manual tranny. Thanks for your help

 

From the interweb....Possible causes:
1. Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
2. Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse
3. Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted
4. Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection Faulty Engine Control Module (ECM)

Basically you need to first check the fuse for the circuit, then check the entire harness and make sure no open or shorts exist. If all of that is good, you likely have a bad sensor (very unlikely this is a ECM issue). This is the sensor after (downstream) the catalytic converter.

 

Good thanks the problem was the 02 sensor got it changed and checked the harness, fuse circuit and and the wires they all seemed fine. Then i changed the o2 sensor number 2 and erased the codes, so far driven 100 miles and everything seems fine no problems no check engine. Thank you very much the truck seems to have gained power as it was running rough for a while very rich and had a loss of 4-5 mpg i think it was in limp mode amd now it seems great again