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code P0171

27K views 7 replies 6 participants last post by  702Johnny 
#1 ·
P0171 System too Lean - Bank 1.

So...what shall I fix/replace? :)

Seems to be not getting enough fuel for the fuel to air ratio then? or too much air?
 
#2 ·
First thing I would do is hookup an OBD2 scanner and monitor the "live datastream" on the o2 sensors and verify it is running lean. P0171 can be anything from MAF being dirty to a clogged fuel filter. You need to check the fuel pressure at the fuel rail and make sure you have at least 45psi under load, then monitor the TP sensor with your OBD2 scanner on "live datastream" mode to see if the TP sensor is tracking properly when you hit the gas pedal or if it's eratic.

Slydog :cool:
 
#3 ·
Slydog's suggestions are good and proper. However, you may have difficulty doing it properly or getting the right equipment if you are a novice like me. I would start by doing two different things:
1) Cleaning the system by using Seafoam and connecting it through the vacuum hose. 2) Also, next time use octane 93 and add an octane booster: this helps to clean the gas system as well.

Seafoam and octane boosters can be purchase at a local auto parts store.

Sorry to say that there is no simple solution to "system too lean." You are going to have to start somewhere and may even get into the technical stuff slydog suggested.

However, the solution can be as simple as bad gas. You may want to describe the car's simptons more so maybe we can offer more help.
 
#4 ·
My 1st gen Kia with 148,000+ miles lost power about a week ago coming up a big hill -- some pinging unless I backed out of the throttle -- really acted like an engine starving for fuel. Right after that, the idle was rough. Low and behold, the filter was plugged. Changed the filter and the power came back, but the idle was still rough - said a word to the Good Lord and dumped in a bottle of injector cleaner. On the next tank full I dumped in another bottle of injector cleaner and said another word to the Good Lord. It seems to be running pretty good now. I figure that God was listening and I picked up a crappy tank of fuel.

So I suggest the simple stuff first - fuel filter, injector cleaner and faith. Worked for me.

Good luck!
 
#5 · (Edited)
Firstly, I wasn't experiencing any symptoms...oddly. Car ran fine.

excellent replies! Actually, the day previous to this post I looked under the hood. I saw that the intake acordian tube had holes in it...so I duct taped over the acordian part of that tube.

Then, a day after this post, the code light went away... So do you think I fixed it? :D

itwasthedog, it's great to get the Master Designer involved in everything we do. :) Nice job!
 
#6 ·
that is a very common problem and i think you fixed it for the time being but i would fix it the right way and get a new intake tube. i know duct tape is a fix-all and everything and it may stay on there for as long as you own the car but i'd play it safe and get a new intake tube. i never fix anything halfway unless it's to cripple it home or to my shop. a system too lean code is usually caused by a vacuum leak after the MAF sensor but can also be caused by a lack of fuel. in this case, you had a leak after the MAF causing the engine to take in more air than it was reading from the MAF which threw off the A/F ratio.
 
#7 ·
yeah, I think I'll look for a more permanent solution to this. :) Also, I hope to find a junkyard w/ a sephia w/ a tach in the cluster. :D
 
#8 · (Edited)
My p0171 code on my 2000 kia sephia 1.8L 5speed.

Ok since this is the first thread that pops up on google, I wanted to post my experience to this thread to help people with the same problem in the future.

I have a 2000 KIA Sephia 1.8L 5speed with 138,xxx miles on it. I bought it and drove it about 120 miles and the check engine light came on. It had a p0171 code. I did not reset the computer, and I kept driving. I noticed that when I would take it easy on the car (& My a/c was on.) that the CEL would go off. But when I am harder on the car (& a/c off.) the light would come on.

So I went to google and started looking at what things could be wrong with the car.
- Intake air leaks (Vacuum leak.).
- Bad o2 sensor.
- Ignition misfire.
- Faulty fuel injectors or fuel pressure regulator.
- Incorrect fuel pressure. (Supposed to be more that 30psi & less than 60psi. - Around 45psi under load.)
- Lack of fuel.
- Faulty Mass Air Flow sensor (MAF).
- Incorrect Positive Crankcase Ventilation (PCV) hose connection.

So.... What did i do first?
I thought, oohh.. I do have an exhaust leak, let me fix that. So I did. Next thing I know 80 miles down the road.... My CEL comes back on and it is the same code.

Next I check the fuel pressure - it was fine.
While I am under the hood, I think to myself... Let me check for vacuum leaks.
I check and find that the ribbed part of the air intake hose has a crack on each rib...
Yep - I bet that is the problem.

So I do some looking around and find that hose on eBay for $35-$40. Local parts stores (Autozone) wants $65. I didn't want to go to the junkyard and get one because I fear I would have the same problem again down the road, and I wanted a more permanent fix.

So what I did for now, (Until I find something better.) is a 3 inch flexible air duct.
I got mine from Autozone for $20. Mine is a "Spectra 8741".
It comes with two rubber fitting and the air duct itself.
That part number if for the black one. They also offer red, blue, and silver.

Since the air duct tube is 3inch's in diameter, I cut the pieces of the stock air intake hose where the hose clamps go on each side and pushed them into the rubber pieces that the air duct came with. The two pieces of rubber are not mounted to the duct so you would have to push the rubber pieces onto the duct without pushing the original hose pieces out of the rubber. Then I reinstalled the hose clamps using bigger screws and I also installed hose clamps on both sides of the air duct where the rubber meets the ducts. I was not comfortable with the seal it had, I though it was going to leak again.

I also wrapped the little rubber hose that connects the air box that sits on the radiator and goes into the filter box with electrical tape. After I washed it.

I did all that and replaced the filter at the same time.

Side note - All of my screws that were holding the top and bottom of my air filter box were broken. So I used screws with washers and nuts and I was able to fix that problem.

Here are some pictures.

Here is the code on my scanner.
Electronic device Technology Cyclocomputer Auto part Electronics


Here is my stock air intake hose.
Vehicle Auto part Car Engine Subcompact car


Here is one of the holes on the ribbed portion.
Coil spring Auto part Suspension Suspension part Fuel line


Here is the new setup.
Auto part Engine Vehicle Car Automotive engine part


Spectra 8741 3" flexible air duct.
Text Material property Font Signage Nameplate
 
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