My 02 f-150 xl V6 4.2liter has 55,889.8 miles on it and I was driving to work today and all of a sudden that "service engine soon" light reared its ugly head. Does anybody know what could have caused this? I think it may be the O2 sensor considering I have not changed it sceince I bought the truck. I know It could be a pllethera of diffrent reasons, so I thought I would get everybodys take on it. I will be looking forward to any info that people may have so dont be shy!

 

easiest way is to pull the code with a code reader, or have it done for free at many autoparts stores like kragen, autozone, etc.

other than that i have no clue whatsoever. i've got 72k and no lights, i know one of my downstream o2 sensors is out but it throws no codes.

hmph.

 

Unless you have the codes read, you might as well call a psychic.

Go have then read, WRITE THEM DOWN (format is Pxxxx where xxxx is a four-digit number), then come back here and search for it (them). If you cannot find relevent information after reviewing the archives, please ask.

There are several codes that are so common they should be pinned to the top of these forums, ie, P0401 and the combo of P0171 & P0174..

Steve

 

sometimes the psychics can't really tell either. code reader is the only way to go, unless you have $13,837 to burn at the dealership for them to tell you that your o2 sensor is disconnected.

Then it's $12 to plug in and $44 to clear the code.

 

Thanks you two I have actually been consulting my Haynes book and Believe it or not it has 2 pages full of codes and their definitions. So, it sounds like I will be going down to autozone or kragen and getting them to tell me what code is coming up. After I get the code depending on which one it is, how should I trouble shoot it from there. The reason I ask that is because I do not know what the definition completly means for example code # PO171 says System Adaptive fule too lean (bank 1) now I know what bank one is, and what to lean is, but how would you go about fixing that?? ...THIS IS JUST AN EXAMPLE...

 

I had the check engine light come on and off for a couple of years. It would go off for a short time if I had a full tank of gas or for some other unknown reason. I had the codes checked three times over the two years and it was PO171 and another bank running lean.
<O</O

I did clean the MAF sensor last fall and it hasn't came on since. (And the bulb is not burnt out)


Incidentally, 3 years ago I did have my exhaust manifolds (with new O 2 sensors) replaced before the problem.


How reliable is the plug in diagnostic systems and are our trucks giving it the right info?<O

 

The codes are very accurate. All the OBD II stuff is required by federal law and is pretty reliable. In my experience, if something is flagged, then something is not right in that subsystem.

For the particula rproblem mentioned here, try and get the code and come back. We'll be glad to help if we can.

 

I am going to call a clouple of local "auto parts" places today and hopefull get down there after work, so I can come home and post whatever codes I get.
I also wanted to give a huge shout out to everybody on the forum for always being so good about posting relevent answers to all of my posts. YOU GUYS ROCK!!!!

 

If you have an AutoZone nearby, they can read the codes at no charge.
Keep us posted.

 

Ok, I just got back from autozone. After work today, I went to Kragen hoping that they would have the obd-2 machiene, but as I suspected, no such luck! So off to autozone it was. I went inside and they gave me the device to read the obd-2 codes, i took it out pluged it in turned the ket to the last click and nothing happened. It is supposed to turn on automaticly after you turn your key to that position, but nothing happened. So I had someone come out and check to see if I was doing it right and sure enough I was, they hot the same results as I did, nothing! So im sitting there and wondering what is going on, this divice looks really new, like out of the box new, so I figured it had to be my truck was the reason nothing was happining, So 20 minitues later after checking every fuse under the dash and under the hood, i find 4 blown fuses, which I go inside purchase new ones plug them in, plug in the device again turn the ket and.........Bamm the thing worked just like it was supposed to. Go figure.
The good news is I only had one Code come up. The code is "PO401-EGR insufficient flow detected". So I am thinking its the ERG valve. So my next question is should a ERG valve go bad at 56,000 miles? I bought the truck with 24,000 and I have never replaced it, and I doubt the previous onwer ever did, due to the low milage. Is there somthing more sinister going on here that meets the eye or is it probibly just time to replace the valve? Or could it be somthing effecting the air flow through that valve and not the actual valve its self???
So there we have it gentelmen..and ladies out there, The forum is now open to answers! Thanks again in advance everybody

 

Read your Haynes manual some more!

You really have to check the WHOLE EGR system.

I had a code 332 on my 94 Ranger for insuff. EGR flwo, but it was a hose coming from the DPFE to the exhaust that was missing its lower half....exhaust gas all over the place! Fixed hose, pulled ECU fuse to clear code and problem solved. Of course, the Haynes lined out what to check...

 

i know there was an EGR TPS, my cousin had the recall performed under warranty on his 01 awhile back

 

I had the same code on my '02 also. After I replaced a $54 egr valve, it ended up being the DPFE sensor. This measures how much flow is actually getting to the engine. It was $34 at my local ford dealer. After this I get a letter from ford about this sensor being in a recall or tsb, and my dealer would replace it for free.I bet your dealer knows about this.You can probably get it for free, if they will admit to the recall. Bottom line call your ford dealer, and tell 'em the code, and tell you know about the recall, and can you get it for free.