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2004 Ford Ranger check engine light always on, no symptoms

How many hundreds of dollars might it cost to get this problem diagnosed? Mechanic says there’s a list of 12 to 15 possibilities, & we’re short on money. No performance problems, & just tightened the gas cap.

 That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P1234) not just their translation into English and post it back here.

Seriously? Advance Auto Parts will read it for FREE? I love these people…thanks a ton for that tip! I’ll do just that, probably tomorrow. Stay tuned!

Oxygen/gas mix might be the problem, according to our mechanic. Husband says diagnostic already completed (it WAS free), but now could be 12 or more other things. We live in a county that does not require emissions inspection & wonder if we need to do anything. Planning trip Pittsburgh to Denver & back in 2 weeks.

Like Joseph said, post the code(s) here, like P0101. Otherwise, we’re just guessing here. The guys at this site can offer good advise based on the actual codes.

The code is P0171. Any ideas?


Unlike the vague but costly ideas of your mechanic, I will give you two low-cost possibilities.
Since this code indicates a “lean” air/fuel mixture (i.e.–too much air/too little gas), the first things to do are to check for a vacuum leak and/or to clean the Mass Air Flow sensor (MAF). Both of these should be low-cost jobs.

If those do not work to turn off the CEL, then other possibilities include a weak fuel pump and an EGR valve that is stuck. These are potentially more expensive solutions, so I suggest that you initially try the first two suggestions.

I had the exact same issue on my 2004 Ford Ranger Edge. I have the 3.0L (Thankfully!)

My problems was the MAF (or MAS). I soaked it in white vinegar overnight (Making VERY sure the plug connector wasn’t in the vinegar!), and blew it out with the air compressor, and everything was fine. AutoZone makes MAF cleanser spray if you don’t want to bother with vinegar.

I’m of the opinion that, and I’m sure I’ll get flamed for this, once you try something, unplug the battery for an hour, plug it back in and drive, and see if that CEL comes back on. If not, you either fixed the problem, or the CEL was indicating a code that no longer applies!