My new 2002 F150 throws a P0 0174 (lean; Bank 2) code. Reset several times; comes back within 25 miles. 5.4l. Researched code info.

Cleaned MAF sensor; checked air cleaner. I don't see any obvious vacuum leaks.

Any hints?

Jim

 

Exhaust leak before the O2 sensor on that side can cause a lean code. Check the EGR tube, it rots at the manifold. Use an unlit propane torch to check for vacuum leaks. Check the elbow in the PCV line at the back of the intake.

Fix your sig, you can't link to Photobucket any more without paying for a premium account.

 

P0174, not P0 0174. Too many zeros. 5 digits, P followed by 4 numeric digits. The first numeric digit can be 0 or 1, 2 is starting to appear on some vehicles, but 0 and 1 are by far the more common. 0 indicates a generic code, all cars that can make the code make it for the same code definition. The causes change from time to time, but the P0 code always is defined the same way. P1 is a unique code. Two automakers could theoretically use the same P1 code, but it might not be for the same definition. The last three digits are always numeric digits.

Back to your P0174. This means LEAN BANK 2. Bank 1 is bank that contains the #1 cylinder, bank 2 is the other bank. On your Ford engine, Bank 1 is on the right side of the engine (where left and right are as viewed from sitting in the driver seat). On a USA car or truck, this is the passenger side, but a Euro spec vehicle, the right is the driver side, so making reference to driver and passenger is not always correct, but left and right are always right when viewed from sitting in the driver's seat. You have trouble with Bank 2, so it is on the left side of the engine.

The MAF measures the intake air for temp and density, mass. This information is sent to the computer where it is used to calculate the fuel injector timing to achieve the correct air/fuel ratio. After combustion, the O2 Sensors monitor the contents of the exhaust to see if the air fuel ratio is 14.7:1, and the computer uses this information to add to the MAF data to trim the fuel ratios. Think of the MAF as a coarse adjustment and the O2 as a fine adjustment. THAT'S HOW IT WORKS RIGHT. When it works wrong and you get the error code P0171 or P0174, then you have a leak in the intake track somewhere that is allowing in air that has not been measured by the MAF. You need to isolate and correct a leak in one or more of the hoses that are connected to the intake manifold on the left side of the engine (remember, not the left side as you lean over the grill). One of the easiest ways to find a leaking hose is called a Smoke Test. Create a smoke source connected to the intake where the MAF normally goes. With the engine off, open the throttle plate so that smoke flows into the engine, look for the smoke to come out somewhere, that's the problem you have to fix.

 

Mechanic replaced fuel filter becuz of low fuel pressure reading. CEL stayed off for a couple days (100mi), bu then came back on. Now they have done a "flush" to clean out carbon, injectors (upper cyl stuff), and replaced intake manifold gaskets (says manifold not cracked). MAF checks out OK.

Going to pick up again today; hoping it's fixed.

Jim

 

I am concerned your shop just guessed at the issue by what was done.
The code is set when the long term fuel trim table 2 in program shifts to the limit set in program.
It means the Ox sensor bank 2 detected too much oxygen in the exhaust.
Clearing the code does not clear the fault.
To really see what is going on, a Scanner needs to be used to take a look. Question is did the shop do that or are they guessing?
A single code like this is most often an exhaust leak just ahead of the Ox sensor.
MAF is common to all cylinders outside of the intake tract.
Fuel filter the same.
Good luck.

 

No, they didn't just guess. They put a scanner on it (of course), and, of course, I'm not stupid enough to think clearing the code eliminates the fault.

They also reset the idle and fuel trims, and installed new PCV valve. None of this is on my dollar as the truck is under dealer warranty.

Jim

 

I would go through the engine with an unlit propane torch and find the vacuum leak like glc said earlier.

I have a feeling it's a cracked hose someplace. Being it a 2002 and it's 2018, I'd bet it's some hidden hose.

Yes it's time consuming for the shop, but it's more time consuming throwing parts at it and making you, the customer, unhappy.

If I was the shop, I'd be all over it doing the basic tests first and testing for vacuum leaks would be my #1 thought when I see a code like that.

 

I'm sorry you took insult to my reply.
I answered based on what you posted.
And no they did not reset the idle because it's set in program and can't be changed..
The tables are zeroed anytime the power is removed from the computer.
You see why I questioned their work and the way you described it?
If it worked, you would not be here asking with still an issue.
Good luck.

 

Well, anyway...not sure if their work fixed the problem; I'm just updating the thread. Work was done Friday, and CEL did not come back on in the 50 mile or so drive back home. So far, so good, but I'm not celebrating yet.

Jim

 

Also, an intake leak that is unique to Bank2 will give this code. You can look at the intake and see which hoses are connected in a way that they will change the air/fuel ratio on one bank but not the other. Most vacuum (intake) leaks will affect the entire engine, but it's entirely possible that you can have a leak that one bank or the other might not see.

 

You should go on eBay or Amazon and search for ELM-327 MODULE, you can get them for Apple or Android, and they connect by wifi or bluetooth, or both. The cost is in the neighborhood of $20. You can find them for less and for much more, less is probably not a good idea and much more doesn't really get you very much. Stick to $15 to $25. Then go to your app store for the device you have and buy TorquePro or OBD Fusion. These will cost you about $5 (five). You will end up with a scan tool for your vehicle that can read and reset the codes, build log files, graph sensor values, and so on. You will know more than you ever dreamed was possible for $30. The app store has some free apps that do most of the same thing, but the free ones do not give logging capabilities, you only get to read codes and reset the computer. This will be the best 30 bucks you ever spent on your tool collection.

 

Well, to wrap this up, it looks like the manifold regasketing fixed the issue. Driven it for over a week, and no CEL yet. Put on quite a few miles (250?) and so far, so good.

Jim

 

Good to hear. Hopefully it stays off and runs good.

 

You still need the ELM-327 module and an app so you can read, diagnose and clear codes as they come up.