PO155 - O2 Sensor Help? What does it do?

[xxbonoxx]

My truck has been driving like a dog recently (2000 Explorer, 2Dr Sport, 4WD, 4.0, 6L SOHC)...It seems to be reving too high before switch gears...and I want to avoid a costly transmission replacement...so I will be installing a speed sensor today as many have said it was a typical fix...THOUGH...when I scan the truck, I only get the following error code:

PO155 - Upstream Heated O2 Sensor heated circut fault (bank 2)

1.) Could this be responsible for my trucks problems? What is this doing to my truck?

2.) Is this something I can fix myself, any advice?

Thanks in advance.

 

[97ford50x]

it means the the front o2 sensor is bad but my advice is to do all of them if you have the o2 sensor socket you can do it

 

[xxbonoxx]

it means the the front o2 sensor is bad but my advice is to do all of them if you have the o2 sensor socket you can do it

What's the worst that could happen if I don't fix it?

 

[97ford50x]

gas mileage goes down and it will run bad and if it is run too long ????????? never run one that long to find out