my check engine light continues to come on (2001 4.2L V6) and I was wondering if any of you guys have an idea of the cause. About 6 months ago my truck through the 171 code " too lean on bank 2" and I changed the isolator bolts, the upper intake gasket, and cleared the code. It hasn't thrown the code since till about 2 weeks ago. one of my best friends is a Ford certified mechanic so I will have help on install once I figure out what the problem is. If any of you have experienced this please advise me on the direction to take. Thanks

 

clean the mass airflow sensor

 

i have a 2001 f150 with a 4.2 and mine threw the same code a couple months ago. "too lean on bank two" could be the oxygen sensor on bank two. that fixxed mine

 

I have a 2001 4.2 and it has had some issues with throwing codes the past 9 months. I replaced a few items and then about 2 months ago I cleaned the MAF sensor. The code did not come back until this past week. Autozone read and cleared the code for me. It reads as follows:

Fuel trim bank two condition
The ECM has detected a rich or lean Air/Fuel ratio condition on engine bank two.
Probable cause
1. If bank one and two are set together suspect a fuel pressure condition or MAF sensor fault.
2. Failed H02S21 (heated oxygen sensor - Bank 2 Sensor 1
3. Ignition misfire condition
4. Fuel injector problem
5. Engine mechanical condition

The truck has 49k on it. I am planning to replace the plugs this weekend. I think that I need to replace one of the oxygen sensors. Which one of the two, driver or passanger side, needs to be replaced? The truck is not misfiring or running badly. My fuel economy does seem to be a bit low. Will replacing the oxygen sensor improve my mpg?

Thanks for your opinions!

 

Assuming your truck has the black plastic plenium chamber, (the black plastic thing between the throttle body and the aluminum intake manifold) there was a TSB about changing the isolator bolts. Remove the upper half of the plenium, remove one of the lower bolts, if it has a black rubber grommet on it, thats the defective type. They were updated with a green colored grommet. At this time keep your money for the proper repair and donate to the O2 sensor stimulous package later. President Obama will personally thank you.

Is my memory correct? 46K miles, I'm at 215K and runs like a charm. Get that condition corrected and enjoy this truck for a long time.

 

Thanks for the reply Bill. I am curious about the bolt. How does it cause a code to be thrown?

 

The bolt holds everything together mechanically, the rubber grommet around the bolt does the sealing to prevent air leaks. Originally it was black, the improved color is green. The bolt and grommets are an assembly and are changed as a unit. Its a little pricey, about $160 out the door.

 

I have a f 150, 2000, 4.6l.when running past 15 minutes,indicator hot water full.
what is the fail,but,when it is stationary does not fail.

 

Huh? is this supposed to have anything to do with the original post of a code 171 fault.

I think you should start a new post, and explain a little better what your problem is.

 

Now Bucko, cut the Newbie some slack. But I have to agree, and by the way, what is a "hot water full indicator"? Must be something with my eyes.