my truck keeps throwing out these 2 codes and nothing I have done seems to fix it!
I have replaced all emission parts under hood (ie: egr, tps, mafs, etc), air filter, vac hoses, all 4 o2 sensors, fuel pump, fuel filter, plugs, coils, oil change, everything i could think of, with exception of the evap..nothing makes the code stay off permanently!
I finally got tired of trying to find it, took it to my mechanic who took it to a more specialized one. Smoke checked it, no leaks. His equip came back with bank 1 #2 o2 sensor bad. (That doesn't explain bank 2 code to me, but ok..whatever, so run with it... )So they replaced. Ecl came back on. Said same o2 was still the issue, so they replaced with a Ford factory part. Ecl came back on! Apparently wires for that sensor check out ok, also.
Im beginning to wonder if the ECM is failing! But thats a rather expensive troubleshooting step!
It runs great! No lagging, hiccups, idles fine, shifts fine, gas mileage is normal..nothing indicating anything is actually wrong!! I live in the mountains, and the drive up the hill would definitely put enough load on it to show some signs of trouble, i would think, but no issues, no matter how I drive it!
I am completely stumped at this point..anyone have any ideas??

 

What exactly are the codes it's throwing?

 

Also what year and engine?

 

This is a a sad commontery of just plain ignorance.
Replace all those parts without knowing anything about the system operation.
System Lean codes for both banks is an excess of air in the intake track that will be common to both banks.
This excess is detected by both front Oxygen sensors as an excess of Oxygen left in the exhaust gas after combustion has taken place.
The rear sensors have no part in this specific issue.
The codes are triggered when the long term fuel trim tables shift 25% showing the system was trying to correct for the excess air.
.
On the other side of this, a lack of fuel will create the same condition leaving too much Oxygen in the exhaust after combustuion..
.Question is;
1. What motor beause this has a part in finding the excess air issue.
2. What is the fuel pressure?
Don't make a well defined issue so hard..
Use a Scanner to look at the long term fuel tables and how fast they shift once cleared..
.
If you take this as an insult, so be it but I gave you what should have been known by all parties.
Good luck.

 

Wow! I was unaware I had to be such a schooled pro to post anything here. I'm just a backyard mechanic. Anymore, just learning as I go, based on what I need at the time. But if I am so ignorant, as you so eloquently stated, and my commentary was so sad, then why bother reading the entire post, and then take time to respond?
And how does one learn anything if they do not ask "ignorant" questions? Or would you rather just have read, "I have (x) issue, how do I fix it?" At least I gave it my best shot first.

I am aware of the system operations, however, when all logical places to start were exhausted, as far as my pea-brain was concerned, i expanded the scope. And i believe in doing more than what is necessary, in regards to replacing parts, in that if there is something else within that system that may be just as old or worn in the vicinity of the work taking place, might as well do that too. Then it doesn't need to be worried about later. And, in my experience, as ignorant as it may be, when dealing with a 17yr old vehicle, with 180k miles, it doesn't hurt to err on the side of caution.

But don't let my ignorance take up your time, because i don't want your input, regardless of what you know!

, whatever, regardless of

 

You are making a big mistake taking on Bluegrass like that. He has helped countless numbers of people here, he really does know what he is talking about. Put your big boy pants on and answer questions that are asked, your issue will get solved.

 

Sorry..
2003 5.4l Heritage model
P0171 & P0174- Lean Bank 1 & Lean Bank 2, respectively

 

I dont need to be insulted just because I ask for assistance! He could have plainly stated the questions, as you did, and left it at that!
And my Big Girl Panties are right where they belong! :0)

 

I think you wrote that the fuel pump and filter were replaced. What is the fuel pressure at idle and under load? You may be able to borrow a gauge at your local auto parts store? Put a couple bottles of Chevron Techron in the gas tank. It's a good idea to do this once in a while anyway.

 

I posted somewhere what ECM"s are compatible with which year engines and their setup. I can't take the credit for the information as another did all the work on this.
With that said, you can get one on eBay by a company out of Minnesota with your VIN number and all programmed for your truck ready to go. The ones I have seen are below $200.00 if you have to go that way. By chance have you made a hard reset to your ECM? Take the positive and negative cables off and touch them to each other to drain the power out of all your systems. Let the truck sit for an hour or more and then rehook back your two cables. See if this code comes back after that.
Other questions:
How old are the injectors in your truck? Are they spraying correctly? Are the filters in the head of them partly clogged up?
(They are in the head of the injector where they pug into the fuel rail. Take one out and look into the top of the injector and there sets a filter that can be changed with a rebuild kit with the extractor) You have to have the extractor to remove these filters and a rebuild kit comes with new caps, filters, and o rings. The kit is around $30.00 on eBay for the 8 injectors rebuild kit with the extractor. They will not throw a code if they think they are working and it is a filter.

Like Bluegrass said, not enough fuel can throw these codes as well and someone did not do the basics on troubleshooting.
I like everyone else on here who has ever turned a wrench make mistakes every day and forget simple things at times as well. Just remember to keep your big girl pants on and keep a stiff upper lip and ask for help when you need it.

 

I sort of knew the OP might take my reply kind-a hard. The hint was in the ending of my original reply.
Iv'e been on these kinds of boards for about 30 years and have experienced about every knock down drag out scrap there is, from many sources.
What people don't realize is that getting angered from a " tell it like it is " reply is really showing the anger at >>themselves<< for not being able to solve their problem and hide it by attacking others for showing it up.
Think about it and try changing it in the future.
No one ever thinks straight under these conditions.
People fight, hurt and even shoot/kill each other because of it, when the problem never calls for such actions.
Good luck.