Prius (Gen 1) :: Lean Condition In Bank 1, Code
Aug 15, 2011
I have a 2002 prius with 130,000 miles on her, and so far so good except for a small problem for the last three months, I get an intermittent P0171 code. I know it means Lean Condition in Bank 1. However, I can run the car for weeks without it coming on. If I go full throttle getting onto the highway for example it may come on, but even then its not all the time. Not sure why only full throttle. But if I drive her gently, I will never see the CEL at all.
Fuel economy is around the usual for me at 46-49 mpg with average speeds of 75-85 mph. I don't think its vacuum related.
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A few months ago I got a CEL, the problem was a lean condition on bank 2. Since then, that problem has happened again two or three times. Yesterday, I got the CEL again and now it's showing lean on both banks. When it was just the single side, I was thinking MAF, but now it's both I'm thinking possibly the fuel pump. The only other thing of note which may affect it is that I'm 90% sure the thermostat has been stuck open for the last couple of years, which presumably affects the map being used, it does throw an "implausible coolant temperature reading" fairly regularly in cold weather.
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2006 f-150 with a 4.6L. Its got 175k on the clock and ran like a sewing machine despite little maintenance other than oil changes. Recently it started running like crap; no power and missing so he borrowed a scanner and it was giving multiple codes. Here's what we have done so far, not necessarily in this order :
1.Checked for vac leaks with carb cleaner (this can be tough as engine runs crappy and hard to detect minor changes in rpms while your under the hood) no leaks detected yet
2. Changed the plugs, all looked good except for one which was heavily fouled and the electrode ate away mostly, I wasnt there and he doesnt remember which one but have a suspicion, more on that in a min
3. Changed most of the COPs and checked them all with a spark tester, all are firing.
4.Cleaned the MAF sensor with MAF cleaner
5. Checked back pressure on the exhaust by removing an upstream o2 sensor and holding a plastic fitting hooked to a pressure gage long enough to get a reading, about 1 lb idling to maybe 2 max when engine is reved, gage is not the best and fluctuates a 1/2 lb or so. Exhaust does not smell of rotten eggs.
6. Changed the fuel filter, it was terrible
7. Ran a bottle of Seafoam in the tank
8. Took the throttle body and egr valve off and checked for carbon stoppage, the holes in the egr were not blocked
9. checked the PVC valve and line and both elbows
7. checked the injector connectors with a noid light for signal, they all flash, checked the injectors them selves with a multimeter set for ohms, all about from 13.5-14.5. This should mean they arent fried but could they still be stopped up? They all sound like they are pumping when you listen with a mechanics stethoscope
9. Changed all 4 o2 sensors as this had never been done anyway
10. Compression check on cylinders, all within 10% of each other at about 180 lbs. When we pulled the plugs they all looked good except for # 7 which was heavily fouled ( I suspect the same on the original plugs) and again with a bad electrode, the part coming out of the porcelin. Intrestingly, this was an autolite plug, the rest were motorcraft, I hoped this was somehow just a bad plug but no change with a new MC plug
11. Changed the injector on #7
The scanner reads lean condition on banks 1 and 2 and random misfires on #4 and # 7 still. Per a troubleshooting tip online, we sprayed some carb cleaner in a small vac line coming off the manifold to induce a rich condition and the scanner showed the o2 sensors go to .900 which is what they are supposed to do per the guide. This means they are functioning correctly and a bonafide lean condition exists. I am leaning towards a vacuum leak around the plastic manifold under the aluminum one, maybe the gaskets but would like to rule out the egr valve, could it be the culprit?
I have even considered the possibility that the PCM is bad, though not likely. I have read to detect a vac leak you can hook the scanner up and spray the carb cleaner around on the manifold and lines with the scanner hooked up watching the scanner PID for the o2 sensors and when they detect the cleaner, they will hit that .800-1.0 meaning the engine sucked the cleaner in and you have found your leak. The exhaust smells rich. If it is a vac leak, you would think it should be a massive leak and not hard to detect, as crappy as the truck runs. I have searched the forums for days and exhausted about all I know to do.
Most important note: early on I suspected low fuel pressure as a possibility; with no schrader valve on the fuel rail and no easy spot to T into the system, we were scratching our heads how were gonna measure psi but the scanner reads absolute fuel rail pressure, gives about 40-43 psi. I hope the scanner is telling us what we need to know there, would prefer a mechanical gauge on the rail!
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I am having a difficult time trying to fix my CEL issue, The vagcom scan says P0171 & P0174 Lean banks 1 and 2. I don't believe both O2's went out I have Checked and cleaned the MAF Sensor did a quick vacuum leak inspection and all seems good. I have a GIAC ST 1 and an AFE intake with noise pipe delete. I can reset it but it returns after a day or so.
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Well I got the ubiquitous "Bank 1 Too Lean" code this morning. Yesterday I changed out the PVC Valve, Elbow and Hose assy.
I changed out the hose from the intake to the canister purge valve on the firewall next to the master brake cylinder, that one was like dust.
Today I'm changing out the rear O2 sensors, but I may change out the fronts when they get them in (very rural area hear).
I'll keep looking for vacuum leaks and change out the MAF sensor. I hate to think it may be the intake....
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I've searched for this and haven't come up with much other than the same error code for a bunch of other vehicles, and a bunch of different responses. My Tacoma is a 2000 PreRunner, 3.4 liter engine.
The exact code I get it is:
P1071
bank 1 system too lean
What this could be?
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I have a P0171 code (lean bank 1 sensor 1) on my 2002 toyota camry 4 cylinder. I don't have any other codes except for an unrelated P1780 neutral safety switch code. It has had both codes for over a year.
I have replaced the fuel filter, the upstream o2 sensor, and the PCV valve. I also cleaned the MAF sensor. The mechanic performed a smoke test and found no vacuum leaks. Did a fuel pressure test and it's normal. Mechanic thought it would be fuel pressure because the car starts a bit slow when cold, but nope. The car runs great and still gets great gas mileage. I've never experienced a misfire in my 12 years of owning the car. I am asking because I am at a loss as to what it could be.
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I recently had some work done on my 2001 VW Passat 1.8T (timing, water pump, major tune up). IT had 72K miles.....
Now I'm getting the following:
Code P0171 Too Lean (Bank 1).
Emission Light turns on / off.
Check engine light comes on and stays on after about 20 miles. Can this be the oxygen sensor?
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Brought home tonight a 2001 Ford Escape 3.0L 24 Valve V6. Bought it from a mechanic who's customer didn't want to put any more money into it. Has 185000 miles on it and it throwing the P0303 & P0171 codes. Cylinder 3 miss and Lean condition bank1.
Mechanic thinks it is a valve seat in the cylinder head next to the fire wall. Before I start replacing the cylinder heads with new remanufactured heads I plan on doing a compression test and leak down test.?
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After installing Banks headers and full exhaust, I took my truck for another test drive this morning. SES light came on about 15 mins into drive and is telling me P0174 - Bank 2 Lean.
So that's the right/drivers side - my list of things to go check
O2 Sensor plug on that side
The MAF
The IAC
Vacuum lines ...
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I've been having this problem since I've gotten the truck about year ago. it has very high long-term fuel trims and it seems no matter what I do I cannot get them to go down my fuel trims at idle are 39 Bank1 and 33 bank2 they go down to around 12>7 while driving what could this mean. And even weirder occasionally I get Bank 1 or bank 2 too lean codes at idle when cold starting???? 1997 Ford F150 4.6 ......
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2000... I have a code P0171 bank 1 too lean. My question is does this exclude anything that will effect both banks? If it was MAF sensor or fuel filter would it set code and say banks 1 and 2 running too lean? In which MAF sensor ohms out correctly. I cannot view fuel trim files. I have looked for a vacuum leak with no luck. I got some cigars to try to smoke it to see if there is any vacuum leaks. Trying to narrowing what i need to checks.
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I have a 2006 Chevy Trailblazer LS/LT 4.2 liter 2wd. I have been trying to get it smoged, but can't clear the code. P0171 - Lean Bank 1.
I've been having a parts throwing contest with it, but it has been winning and my wallet is losing.
I have changed the air filter, cleaned the MAF sensor, changed both O2 sensors, changed the secondary air valve and relay. I've done the carb cleaner spray test around the intake and vacuum lines, with no spikes in RPM.
Most recent try was a couple bottles of Techron concentrate with premium chevron gas.(still waiting to see if the code hits again)
Next steps are checking the intake bolts(to see if they are torqued) and intake gaskets, check for exhaust leaks at the exhaust manifold, and checking the MAP sensor.
Freeze frame data from the most recent hit on the code is below.
***Fuel system 1 - CL***Fuel system 2 - NA***Calc Load(%) - 30.2***ECT(deg c) - 48***STFT B1(%) - 3.9***LTFT B1(%) - 22.7***MAP(kPa) - 33***Eng RPM - 809***Veh speed(km/h) - 0***Spark Adv (deg) - 10.5***IAT(deg c) - 20***MAF (G/s) - 5.82***TPS(%) - 15.3***Air status - NA.
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We have a 2003 Passat 1.8t. Had the Check engine Light come on. Went down to AutoZone and hookeded up the OBDII reader. Came up with P0171, Fuel System for Bank 1 was too lean. Probable causes:
1. Fuel Pressure of MAF (If Bank 1 & Bank 2 set codes together)
2. O2 Sensor
3. Ignition Misfire
4. Fuel Injector Problem
Car has 60K - has always run well. Wife says she thinks it's running a bit sluggish. I rarely drive the car, but I think she's right. Car is not missing or running rough.
I cleared the code & started the engine; Check Engine Light is off; then looked at the codes and I find a P0171 (Pending). She tells me that the light has been on before & then gone away. So I guess it clears itself, but eventually comes back.
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I got an 04 Nissan Sentra and I got a (P1273 Nissan - Air Fuel Ratio Sensor 1 Lean Shift Monitoring Bank 1) code that popped up on it. Looking to see what the probable cause for this code to pop up? Is this a rare code that popped up on this car? There's no noticeable symptoms going on with the car.
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I keep getting a lean bank code. I have cleaned tb and replaced one of the rubber lines. It only comes on when I take a good ride with the truck. Not sure what else it could be. I'm thinking O2 sensor maybe.
2008 F-350 5.4 3V. 65k miles
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I just bought a 99 f150 and the check engine light came on with code p0171,system too lean bank 1. It runs and drives fine but has a strong smell of gas when I shut it off.
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2003 f150 supercrew with 166,000 miles on it. Daily driver. Service light randomly comes on and when code reader was put to it shows "left bank running lean." Will clear it and will randomly come back on. Truck seems to be running fine. No issues engine. Bad sensor? Or bad injector? Maybe way to test?
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So I just replace my Cat. Converter with all new sensors in them. I just replaced my spark plugs. (I'm knocking out these check engine light problems) and I think I'm getting close to the root as to why these other parts went bad. Why my o2 sensor would be stuck on "lean" ....
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I own a 1996 Mazda Protégé with 128,000 miles. I had it in for a check of a sewing machine sound. The mechanic tested it and found, among things, a "lean running condition". What does that mean?
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My 2000 ranger with the 3.0 is only getting around 10 or 11 mpg. It's got a check engine light on but the scanner just says lean condition. The truck also has a rough idle. I've replaced the fuel pressure regulator and fuel filter.
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