p0171 and p0174

check fuel pressure with a gauge as that can cause it as well auto parts rent it. also check for a vacuum leak.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

this guide can help as well

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Please run down these guides and report back.

The PCV line and the main rubber connectors are common causes of lean codes in that truck. Some of them are not easily accessible.

It was the MAF sensor thanks for the guides helped me fix it

Nice work, we are here to help, please use 2CarPros anytime.

Vehicle had a rough idle for some time. Then I had an overheating problem, the thermostat housing got damaged. Installed a new Housing with a new Thermostat then vehicle started working bad, rough idle and the Chek engine light came on. Had the MAF, Coolant Temp, TPS, Temp Sensors replaced and the Spark plugs and ignition Wires replaced. worked a little better while it was cold but as it heated up it started working with a rough idle and sometimes cuts off. Whiel checking on it I noticed the Exhaust pipes were Flaming red hot. I removed the Catalytic converter and inspected it, the same thing happened So I replaced the Led wires and the converter stopped Flaming. But the check lights is still on and using a ODB2 I got a P0171 registered. Would the O2 sensor alone solve my problem? Thank you for any help.

The O2 sensor is what detects how rich or lean the engine is running. I would try that first. Now, for the converter that was red hot. that is usually an indicator that it is plugged. Make sure it is free flowing.

I getting codes po171 & po174, I changed the fuel filter because the truck sits most of the time and reset the codes. this lasted about half a day, It was a daliy driver until a year ago.

When I bought it a egr code came up the first month, so I had a mechanic look at it he cleaned it and it was fine. but that was back in 2006.

Both codes are for a lean mixture on both banks. What I recommend is checking for vacuum leaks.

Let me know what you find.

Joe

I have the SOHC engine. I am getting the following seven codes: P0171, 0174, 0175, 0303, 0304, 0305 and 0306. Any help at all would be appreciated. Thank you in advance. I recently replaced all the spark plugs and was getting 171, 174 and 303. Now I have the above seven codes. Just trying to see where to begin in repairing this rough idle.

Additional: rough idle and fuel smell. Where do I start.

The P0171, P0174, P0175, are all lean codes. First thing would be to check for vacuum leaks, especially at the intake manifold upper/lower junction. The O-rings love to fail and suck in extra air which gives you a lean mix and will give you the codes you have.

P03XX codes are all misfire codes for each cylinder.
If you only had the 303 (cylinder three) code and got the others after a plug change you may want to check the plugs you used and the coils. But do that after you repair the intake leak.

Issue resolved! Thank you turns out the number 3 plug was bad, intake hose you mentioned was split and also cleaned the throttle body and she accelerates quicker than ever.

It's getting to the point that parts stores should have test equipment to test all of the "new" parts as they arrive from the factory. I'm not sure what the current percentage of parts that "failed out of the box" is but it seems to be getting worse.

Good to hear you got it repaired. Vacuum leaks are a real pain. They are extra air that the computer doesn't monitor through the MAF so you get a lean condition.

I have a 2000 ford explorer 4.0 OHV. I had 2 codes come up for PO171 and PO174. when i looked them up on google it lead me to believe i needed a intake manifold upper and lower gaskets. after replacing them. i got one of the codes back PO171. where do I go from here?

common to get the p0171 code after doing that. if you are not careful putting the manifold back in or dont properly torque down the bolts it will leak. usually it leak due to improper operation by nicking the orings trying to get manifold back in. quick check is to start vehicle and spray some propane or brake cleaner around the manifold. if idle changes you found the leak. if not then you may just have a bad o2 sensor or exhaust leak.

the cel has been on for 2yrs and my truck runs great it has had the same codes po171 po174 (lean condition banks 1 & 2 ). i need a smog this yr so i need the light off. i have to go to a star station per the state. i couldn't find any vac leaks etc,so i disconnected the bat so it would go out for the smog test. well i passed all the tests except the function test b-cuz i erased all the monitors needed for that part of the smog test. so the tech told me it was prob the mass airflow sensor , so i spent 130,00 on a new one while the light was still off i put it on and started a drv cycle to set the monitors so i could get a retest smog. so durning the drv cycle the cel came on same codes so i took the mas back and put the old one back on. i then paid the tech 65.00 to do a diagnostic check to find the prob he found a ever so slight leak in the intake manifold gasket area. so i paid a mechanic to change the gaskets and i barely got the truck home still running great just like always and the friggen light came on again. i'am at my wits end. i have been dealing w/ this since aug 2nd . i have read and watched countless videos i have searched countless sites for ans. all to no avail. however, i have learned alot about mechanics and my truck. but thats not getting the cel off. do u think maybe the pcm is out of wack since the light has been on so long and the truck has ran great the whole time. i can't find anything wrong cuz there isn't anything wrong except the computer is wack . so can u p..............lease help me find the problem ? nobody else has been able to. i am out of ideas, out of $ ,out of time and out of my mind w/ this problem and i know more about mechanics then any female should (lol) . oh i almost forgot to mention it may not matter but, then it could be the key to the ans, ( what the hell do i know ) for the 2yrs that the cel was on it showed 2 codes 171 and 174 i know they r related to the lean condition banks 1 &2 but after the intake manifold gaskets got replaced and the light came back on it only showed the po171 code in the stored codes and under the pending codes it showed the 174 code but the total # of codes under diag was 1 code (po171) b-4 it showed 2 total and both were under stored and nothing under pending. so now im all screwed up. i don't know if that makes a bad situation worst or what. please please please help me.........

When he found the leak did he use a smoke machine and do a smoke test to find the vacuum leak?

i believe he used carburetor cleaner and he appeared to be very skeptical about finding a leak ,like he wasn't quite sure that there was really a leak but he couldn't find any place else that leaked. he even mentioned that he was wrong about it being the mas. the thing is that the gaskets were jacked ,torn ,glued etc, in the area he thought he detected the leak ,yet the cel came back on. with a quickness too. unlike b-4 it would take 2 drv cycles ,this time not even 1. do u think that part of the prob was corrected by replacing the gaskets , thats y only 1 code p0171 shows and not the po174?

From what you just told me it needs to be smoked to kook for vacuum leaks.Especially since you said the light comes on quicker now.

Hi,

Engine miss during idle and acceleration. Codes p0171, 174 are coming.

kindly let me know what could be the cause.

Thanks.

Your trouble codes p0171 & p0174 are for the fuel system too lean on bank 1 (p0171) and bank 2 (p0174),would say it sounds like a fuel deliery problem.
Check for a restriction in the fuel system. Have your changed your fuel filter lately? Also check fuel pressure, should be 35-45 psi for your vehicle.
Just a few ideas to start with, let me know if this helps or you have any other questions.
Thank you,
Dan

yes, it fuel filter is changed recently. Spark plugs, cables, engine oil, air fuel/gas, oil filters changed few days back.

Good to hear you are keeping up on the maintenance. Check the fuel pressure, low fuel pressure will give you the symptoms you describe. If you do not have a fuel pressure tester most parts stores like AutoZone, Advance, etc have a tool rental program.
A restriction in the fuel system will also present like this, look for kinked lines, hoses or a damaged fuel rail.
Clogged fuel injectors are also a possiblity, but they usually do not clog all at once and ususally give you a miss fire code (generally cylinder specific)
also check the fuel pressure regulator.
It still sounds fuel related to me but one other possibility is the PCM is recieving signals from the oxygen sensors that the system is running lean so it is sending more fuel to the engine than it needs. It would give you a very sluggish acceleration and poor idle because the engine would be operating "flooded".
symptoms of this would be a drop in fuel economy and if very severe the oil may have a fuel smell and the plugs, when pulled, would have a black appearance and a raw fuel smell. Normally the system would catch this & give you an oxygen sensor code but have seen it happen without the o2 failure code...it ended up being corrupted data in the PCM. Not saying this is your problem but if all the above fuel issues come back ok, this would be the next step I would take.
A lot of info, I put it in order of probability.
Let me know if it helps or you have any questions.
Dan

Engine Performance problem
1996 Ford Explorer 6 cyl Four Wheel Drive Automatic 119K miles

I tested the DTC codes and found that I have a P0171 System Too Lean situation. The rest of the data is Fuel System = Closed Loop, Calculated Load 21.9%, STFT Bank 1 = 21%, STFT Bank 2 = 18.7%, RPM 768.
I replaced the left head and gaskets last December. would this be a bad sensor or something wrong with the fuel rail? Possible vacuum leak? Not sure where to go from here. Thanks for the help.

yes I would check for a vacuum leak, it doesnt seem like too big of a difference in the readings but big enough to trigger a code, which indicates a possible vacuum leak, also check that o2 sensor on bank one, could be a little weak causing a false code.

I found the green o-ring crushed inbetween the upper intake and an exhaust tube that connects to the header. Its about $7.00 for a new one.

wow, awesome. have a good one. thanx for writing