I went to my friendly Autozone to have my codes checked due to a check engine light. I've got a "171 Bank 1" and "174 Bank 2", "Too Lean". The guy thought it was a failed oxygen sensor near the exhaust manifold. Does anyone have a shop manual that can confirm that? Anyone have a similar experience? I've got a '98 Expy, 5.4L.

Thanks,
Steve

 

Just to clarify, the codes must actually be P0171 and P0174.

 

Hey. I have the same problem with my wife's 98 Expy XLT 2DR 5.4L. Autozone told me the same thing but suggested that I had a leak in the fuel injectors (not likely. Unless Murphy's law says both banks have at least one FI with a leak). I'd be interested in knowing what you find. Our Expy has 88K on it but the Check engine light came on at around 70K. The only thing I really notice is that the engine will ping under light load. When Autozone checked the codes, I had them clear the codes thinking I must have had some bad gas at some point. But the light came on the next day.
Keep in touch. If I find anything on my end I'll let you know.

 

Hey guys i purchased a 98 expy with about 90k miles in almost mint condition. Before purchasing i ask the owner if i could take it into a dealer to have it checked over before buying. I had a friend that worked at the dealer ship where i took it and he was able to get one of their guys to look it over and hook it up on the computer. My check engine light was on just like you guys. When hooking it up he discoved that it was a DPFEGR sensor. It is found under the plastic piece that has 5.4L on it, over the throtle body. It has a two wire plug and two rubber hoses that connect to it. I replaced it and it turned the light out and it hasn't been on since. One thing i did notice when it was on is that it seemed that my suv surged sometimes meaning that it felt like something was robbing the power from it at times while i was driving. Another thing if you disconect the battery for about two minutes it will turn the light off. I think the sensor cost me around $80 at the ford dealership.
One thing that i recommend all of you to purchase is a haynes manual. It is one of the best investments ever.

good luck
britton

 

 

Hey guys, thanks for the input. I haven't been around for a while so let me get you up to date. I took Autozone's advice and decided to change my oxygen sensors. Of course this is before I realized what was all involved. I was under the impression there were only two in the exhaust system, one on each side (passenger and driver). In reality there are two upstream and two downstream, one each side of the exhaust. Upstream is before the catalytic converters and downstream after. From what I have read, the upstream checks the fuel mixture while the downstream checks the cat efficiency. I started changing out the downstream prior to realizing the upstream existed. In reality, the downstream should have nothing to do with the codes I was getting since they had to do with fuel mixture. To make a long story short, I changed out the two downstream sensors, disconnected my battery to reset the codes, and haven't had a check engine light for two weeks and probably 800 miles. I began to wonder whether Ford has the check engine light turn on at a specific mileage to make you bring it in to have checked. I've read and heard about other car manufacturers who do that. From the sounds of it, that probably isn't the case since I've heard of nobody with Expy's with the same experience at 60,000 miles. The light may come on again someday, but who knows.

Here are a couple of tips I've learned along the way from the school of hard knocks and people in the know:

1) Oxygen sensors in exhaust sytems are typically a total bear to get out. My best advice is to apply heat and purchase the special deep socket designed to remove them. It would probably even be worth taking it to a mechanic to have him remove it. I spent countless hours getting the first sensor out.

2) The codes you can get from Autozone will typically only get you so far. There are tests called "pinpoint tests" that need to be done to find the exact problem. If I had to do it all over again, I would have taken it to the dealer and had them run diagnostics for $100 or so. Like most guys on this board, I would much rather take care of problems myself than get stiffed by a dealer, so that's a hard statement for me to make. If my light comes on again I will go to the dealer, after a free check at Autozone just to get the info.

Keep me posted with updates on your situations. Knowledge and experience is king when it comes to car repairs.