Windstar 2000 3.8l O2 sensors engine check light - 56K miles

Hi,
I had the diagnostic code read at a local Autozone and it reported both a P00171 and P00174 error, which means all 4 O2 sensors (bank1 and 2, before and after) are bad (running too lean). Can this be a false
reading? How can all 4 sensors go out at exactly the same time? Is that possible/probable?
Someone suggested replacing the fuel cap on some fords sometimes fixes the problem....any comments on that?
Another problem I have is understanding the terminology.... Looking at a diagram printout they had given me at Autozone, it shows 3 BEFORE sensors (B1S1, B2S1 and B1S2) and only 1 AFTER sensor (B1S3). I cannot see the 2 before and 2 after split/designation some online auto part stores are referring to. I don't know which replacement parts I should order, 2 before and 2 after sensors, OR, 3 before and 1 after ?!?!
Will the check light turn off automatically when the faulty sensor(s) is replaced or does it need to be electronically reset?
Any help will be much appreciated! Thanks Neil
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odds are you need to complete the TSB for 99-00 windstars to keep oil out of the intake. I used to have an excellent link for this procedure, has the TSB, full parts list, everything. Hopefully someone else here has the link or I can find mine.

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here's one link http://www.cartrackers.com/Forums/live/fordwindstar/1875.html
if this is your cars problem and you do decide to do it you can get all of the parts except the valve cover off of rockauto.com and save a bit of money compared to the dealer, afaik the valve cover is a dealer only item, maybe $60?

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On 20 Jan 2007 09:08:32 -0800, snipped-for-privacy@hotmail.com wrote:

No, it means the upstream O2 sensors on both banks are reading too lean. This is another of those cases where the O2 sensors MAY bve bad, but more likely the engine is actually running too lean. It could be as simple as a vacuum leak, or a bad fuel filter, or any other fault that could cause the engine to run lean. Easy way to find out, just point a propane torch, unlit, into the intake and see if it richens. You need an OBD2 scanner to be able to tell - just a code reader is useless for this.

Throw money at it AND THEN take it in for repair when it doesn't fix it, or pay someone smarter than yourself to determine what the problem is in the first place. Generally cheaper to pay someone FIRST.

It will need to be reset.

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