Mechanics

CODES P0171 AND P0174 STILL ON??

1999 Ford Expedition

Engine problem
1999 Ford Expedition V8 Four Wheel Drive Automatic 153000 miles

I have a 99 Ford Expedition, 4WD, has the 5.4L engine and about 153000 miles. When I got it it had about 127000 miles two and a half years ago. The only thing we have changed is the alternator about a year ago and the idle control solenoid just before that. Also we had the cluster gauge replace in October. Don't know it that was needed information but it might be.

The check engine light came on about the end of November and I had it diagnosed and was told it was a bad O2 sensor. One in front of the catalytic converter. But before we had a chance to change them the light went off. Well it being Christmas we decided to save money and wait. Well imagine that it came back on right at the end of December.

I went to Auto Zone and this time (I really wasn't paying attention the first time) I asked questions and got the print out it was codes P0171, P0174. Which what I had read said it they show together suspect the Mass Air Flow Sensor.

So my dad (he has been helping) got 2 O2 sensors (the front ones) and we changed them on the 5th. Well the light was still on but we suspected it was the MAF sensor as well and we had to order one. So they changed that out on the 13th (last Sunday). And the light was off for about a day. So when it came on I went back to Auto zone last night and it pulled the same 2 codes. I had the guy erase them, he told me it there was still a problem that it would come back on. And it did this morning.

I am about to say screw it and get a new car but I really like my expedition. But it is costing me a crap ton!

Do you have any ideas?

We are going to check the vacuum lines (what is the best way), and my dad is getting to back 2 O2 sensors. I also called the local Ford dealership and they suggested that the air filter might not fit right because it is an after market one. So I am going to pick a Ford one up tonight.

I am a girl so help is appreciated.
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Short_angel_101
January 15, 2008.



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