Hello all,
Took the '99 Ford Windstar ( 69k miles ) in for transmission service at a well respected, local independant shop. During service, they ran the scan tool and reported two trouble codes unrelated to the transmission.
Codes are PO171 and PO174.
My Haynes manual decodes them as:
PO171 = "System Adaptive fuel too lean (Bank 1)" PO174 = "System Adaptive fuel too lean (Bank 2)"
and if I'm reading
If the Haynes manual is to be believed, there are 4 HO2S's, 2 for each bank, 1 upstream (in the converter) and 1 downstream. Haynes gives details on how to backprobe and look for 100-900 mV varying signals.
I've been unable to find any info yet in my Ford Factory Service manual for this issue or these codes, but they are thick and sometimes not intuitive to me...
Drivability is good, although we have noticed some knocking under load of late. Gas mileage is a bit low, but not noticably different than before the codes were reported.
Should I just jump in and probe the sensors? Can one typically purchase or borrow the "special tool" for their removal and installation? Or is there another place I should be looking? Also, how important is it to clear the codes and look for a re-appearance to insure that these aren't just anomalous? We have no "check engine" light, etc.
As always, any advice appreciated.
Regards,
Powell in Florida