I have a 97 F-150 4x4 with the big 5.4L motor in it. The other day the Check engine light came on so I took it to Advanced Auto Parts and they read the codes and told me it was the O2 Sensor. I will post what the code if someone can confirm that it is the O2 Sensor that would really help me out. I don't think it is that particular sensor becase it has not affected the perormance of the truck at all. No spitting sputtering or running rough. So here is the code........

Trouble Code OBII (Alpha) P Code

Troubleshooting PO171
The PCM has deteremained that during testingthe fuel system for bank 1 was too lean. (Bank 1 identifies the location of cylinder #1 while bank 2 indentifies the cylinder on the opposite bank)

Please help I would like to fix this as soon as possible.

 

Most likely you have a vacuum leak that has, so far, only showed up on one bank.

It is unlikely to be the O2 sensor.

Steve

 

Autozone is nice for the free code scan, run like hell as soon as they start making suggestions on what you need to buy to fix your problem. Autozone is out to sell parts, not fix cars.

Like Steve said, more than likely, you've got a vacuum leak. Start with checking the PCV tube that runs from the passenger's side valve cover to the rear of the intake manifold. Inspect all the rubber elbows closely.

 

PO131 - PO161

Are O2 speciific codes