1999 Ford F-150 Error P0171

Tiny
PLATINUMKANIKAS
  • MEMBER
  • 1999 FORD F-150
  • 6 CYL
  • 2WD
  • MANUAL
  • 102,500 MILES
I have tried fixing this error for a while, but no luck. According to the print out at Auto Zone, there are four things that may have caused this error, I have done 2, used full system fuel injector cleaner, and cleaned the MAF sensor. The other 2 are o2 sensor problems, and ignition misfire.

What do I need to remove the o2 sensors so I can swap them out to see if the error changes? A special tool? or a certain size wrench?

Thank you,
Justin Garcia

Do the sensors look damaged?


http://www.2carpros.com/forum/automotive_pictures/164623_o2_sensor_1_1.gif



http://www.2carpros.com/forum/automotive_pictures/164623_o2_sensor_2_1.gif

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Sunday, March 2nd, 2008 AT 9:31 PM

3 Replies

Tiny
SERVICE WRITER
  • EXPERT
I don't see damage, there is a special wrench for this. There is a slot cut into it to allow the wire to not get pinched. The parts sore should have it in stock. The po171 often turns into a MAF sensor, cleaning doesn't always work.
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Sunday, March 2nd, 2008 AT 9:38 PM
Tiny
FLEXY5
  • MEMBER
Something else to consider is the fact that you are only recieving lean codes for one half of the engine. Typically MAF failures result in lean codes on both sides of the engine. Since this engine has molded intake gasket you may have a leaking intake. It's not a severe leak since you are not getting misfire codes as would also be the case with inadequate fuel from the injectors. Try spraying a carb cleaner at the base of the lower intake while the vehicle is running. If the engine changes the way it runs then that is your problem. If it doesn't let me know and we can go from there. Either way, you will waste your money if you replace the O2 sensors. I can guarantee that will not resolve the concern. Check the intake on the passenger side and post back the results
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Sunday, March 2nd, 2008 AT 9:55 PM
Tiny
PLATINUMKANIKAS
  • MEMBER
The problem started when my brother was driving it. I was in the truck with him, it was nighttime and we hit a puddle going about 65-70mph. About a minute after hitting it, the "service engine soon" light came on. I'll get some carb cleaner and check it out tomorrow. I'll let you all know if I find something out.

- Justin Garcia
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Sunday, March 2nd, 2008 AT 10:03 PM

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