P0171: System too lean (bank 1)
Apr 1, 2006, 07:46 PM
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P0171: System too lean (bank 1)
I pulled this code today after filling my gas tank. I removed and replace the gas cap, and erased the code. Later on, the same code came up. I removed the gas cap, but didn't hear that normal vapor release sound associated with it. Maybe my gas cap seal is bad?
I googled the code and found some information saying it could be the MAF, and i will take that out tomorrow and clean it. Also, I was wondering if our fuel filter is in-tank.
The only mod affecting fuel that i have installed is rrm's cai, and the filter is clean.
I'll update as i go, meanwhile, here is the info i found. If anyone has vanquished this foe, please let me know!
-scott
I googled the code and found some information saying it could be the MAF, and i will take that out tomorrow and clean it. Also, I was wondering if our fuel filter is in-tank.
The only mod affecting fuel that i have installed is rrm's cai, and the filter is clean.
I'll update as i go, meanwhile, here is the info i found. If anyone has vanquished this foe, please let me know!
-scott
What does that mean?
Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.
Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
Symptoms
You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.
Causes
A code P0171 may mean that one or more of the following has happened:
Possible solutions include:
Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.
Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
Symptoms
You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.
Causes
A code P0171 may mean that one or more of the following has happened:
- The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
- There could be a vacuum leak downstream of the MAF sensor.
Possible solutions include:
- In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
- Inspect all vacuum and PCV hoses, replace if necessary
- Check for a dirty fuel filter and proper fuel pressure
Apr 1, 2006, 10:38 PM
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hmm up until now i'm the only person on the evom to get that code with the RRM CAI... I drove a whole summer with it.. no problems.. I just reinstalled my CAI a couple days ago and reset my ECU properly (idle 15 mins, drive under 3000 rpms 15 mins) and havent had the light come back on yet.
Apr 1, 2006, 10:43 PM
#3
From the service manual CD:
You had *just* filled up? I wonder if you got some bad gas..?
DTC P0171: System too Lean
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Mass airflow sensor failed.
• Injector failed.
• Incorrect fuel pressure.
• Air drawn in from gaps in gasket, seals, etc.
• Engine coolant temperature sensor failed.
• Intake air temperature sensor failed.
• Manifold absolute pressure sensor failed.
• Barometric pressure sensor failed.
• Exhaust leak.
• Use of incorrect or contaminated fuel.
• Harness damage in injector circuit or connector damage.
• ECM failed. <M/T>
• PCM failed. <A/T>
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Mass airflow sensor failed.
• Injector failed.
• Incorrect fuel pressure.
• Air drawn in from gaps in gasket, seals, etc.
• Engine coolant temperature sensor failed.
• Intake air temperature sensor failed.
• Manifold absolute pressure sensor failed.
• Barometric pressure sensor failed.
• Exhaust leak.
• Use of incorrect or contaminated fuel.
• Harness damage in injector circuit or connector damage.
• ECM failed. <M/T>
• PCM failed. <A/T>
Apr 1, 2006, 11:14 PM
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Yes, i literally just filled up, started the car, pulled onto the street, and my girlfriend asked me what that "service engine soon" light meant. I was around 1/8th of a tank before filling up. Tomorrow i will clean the MAF, reset the ecu and run it through the cycles.
I know in some cars fuel injector cleaner is actually not good to use, like in my old sentra. It stated clearly in the manual not to use it. Is it the same case in this car? I would go check the manual right now, but its raining and cold...
well, bed now, fix car tomorrow. Thanks for the input thus far.
I know in some cars fuel injector cleaner is actually not good to use, like in my old sentra. It stated clearly in the manual not to use it. Is it the same case in this car? I would go check the manual right now, but its raining and cold...
well, bed now, fix car tomorrow. Thanks for the input thus far.
Apr 1, 2006, 11:31 PM
#5
Personally, I'd siphon almost all the gas out of it and dump it into my truck, then go fill up at a different station.
I don't recall reading any specific warnings about injector cleaner in the manual. I don't think that's your problem, though. Too coincidental that you just filled your tank.
I don't recall reading any specific warnings about injector cleaner in the manual. I don't think that's your problem, though. Too coincidental that you just filled your tank.
Apr 2, 2006, 12:46 PM
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so after clearing the code and resetting the ecu, and a few hours of driving today, no more code. I didn't clean the MAF yet. I'll wait and see if it comes back on. If it does, i'll syphon all the gas into my impreza (which almost has a full tank now, guess its time to hit the trails...) then go refill somewhere else.
Apr 2, 2006, 02:20 PM
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I must be invisible...
I have had this code come up like a dozen times...
I posted about it in a few topics and got no help.
Everytime the "Service Engine Soon" light comes on the next day i just reset the ECU to get it to go away.
I have had this code come up like a dozen times...
I posted about it in a few topics and got no help.
Everytime the "Service Engine Soon" light comes on the next day i just reset the ECU to get it to go away.
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Apr 2, 2006, 05:41 PM
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Its alright. Its not a big deal.
Everytime i have my cousin pull the code we get P0171. I have only reset the ECU twice, once when it was colder out and again when the weather broke and it was around 50 degrees.
Everytime i have my cousin pull the code we get P0171. I have only reset the ECU twice, once when it was colder out and again when the weather broke and it was around 50 degrees.
Apr 3, 2006, 07:29 AM
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no dont add injector cleaner to your car. it is bad for all cars with an egr valve. (all production cars noadays) as far as the code goes. i highly doubt it is from the cas. you will get the same code if the filter comes off you sri. check to see if all the connectors are tight on your intake and that all the vaccume lines are connected and not leaking. this code can be an intermittant code.
Apr 3, 2006, 02:53 PM
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Originally Posted by mitsutech005
no dont add injector cleaner to your car. it is bad for all cars with an egr valve. (all production cars noadays) as far as the code goes. i highly doubt it is from the cas. you will get the same code if the filter comes off you sri. check to see if all the connectors are tight on your intake and that all the vaccume lines are connected and not leaking. this code can be an intermittant code.
The code definately isn't going to go away on its own (
), it came back after another erasing. I'll also check to make sure my filter didn't fall off. I have to stop breaking cars so i can start fixing them... 
Apr 3, 2006, 06:40 PM
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Originally Posted by Boeturbolancer
sounds like you may have an intake leak which is allowing unmetered air into the system... causing the lean condition.
You should do a pressure check to see. Get a plug for the filter end and pressure test thru the breather port.
You should do a pressure check to see. Get a plug for the filter end and pressure test thru the breather port.
thanks.
Apr 3, 2006, 09:34 PM
#14
yes after the mas sensor. You can fashion a plug for the filter end of the CAI. Then use the hose connection that's connected to the valve cover in order to pressure test everything. This will let you know if there is a leak around the MAS itself... after... intake manifold, etc...