What component causes a p0171 system too lean bank one error code?
03-12-13, 12:19 PM
#16
http://engine-codes.com/p0171_lexus.html
Either click the link, or copy and paste the above web address to your upper address bar, and click the go button. Good luck!!
Either click the link, or copy and paste the above web address to your upper address bar, and click the go button. Good luck!!
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Cjet (03-10-18)
03-13-13, 09:52 AM
#17
funny, its almost like saying wear of break pads is a known problem. one wears slower than the other, but fundamentally both are wear and tear items, like almost everything else on a car. O2 sensors are rated for 100-150kmiles depending on the car, i would call it a failure only if sensors needed replacement below that mileage - otherwise its a service item.
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samsonn25 (08-09-19)
03-18-13, 01:55 AM
#18
Driver School Candidate
Thread Starter
http://engine-codes.com/p0171_lexus.html
Either click the link, or copy and paste the above web address to your upper address bar, and click the go button. Good luck!!
Either click the link, or copy and paste the above web address to your upper address bar, and click the go button. Good luck!!
03-18-13, 02:00 AM
#19
Driver School Candidate
Thread Starter
I honestly don't know why you would have started replacing all of those parts in the first place when you have the added diagnostic information of having a v6 with two oxygen sensors. You can obviously rule out a loose air filter hose, fuel filter, fuel pump, oil&filter, and the MAF simply by realizing that you are getting a lean signal from only ONE bank. (don't understand how the VC gaskets would cause a bank lean signal, I'm thinking the shop you went to isn't very well thought of in your community)
(sorry for the long post)
(sorry for the long post)
02-11-14, 03:19 AM
#20
Driver School Candidate
Thread Starter
In my limited experience an P0171 is an O2 sensor failure. I have two 99 ES300's. Both showed P0171. In both, replacing the O2 sensor fixed the problem. Most people say the P0171 is a MAF problem. Not for me. It was the Bank 1 sensor 1 [Air and Fuel Ratio Sensor (O2 sensor)]. O2 sensor failure is a common problem.
Additionally it was the same for my 95 Camry V6 1mz-fe engine. That's the same engine the ES300s use.
Additionally it was the same for my 95 Camry V6 1mz-fe engine. That's the same engine the ES300s use.
02-11-14, 06:02 AM
#21
An Air Fuel ratio sensor is basically a more sensitive (and more expensive) oxygen sensor.
The 99 ES300 has 2 Air Fuel Ratio sensors and one Oxygen Sensor. The AF sensors are the two located closest to the engine. Also called upstream sensors, so 1 bank-one and 1 bank-two upstream AF ratio sensors.
The Oxygen sensor is located on the exhaust. It's also called the bank one downstream sensor. It is located under the driver's seat.
This information is for the 99 ES300. Earlier versions only had oxygen sensors, two upstream oxygen sensors and one downstream oxygen sensor.
Go here, http://www.densoautoparts.com/find-m...icle-selection to see what you need. Denso is the original equipment manufacturer of these sensors. If you need a sensor but a Denso.
Denso sells universal and an OE style sensors. The OE style is easier to install. The universal style requires the re-use of the electrical connector.
The 99 ES300 has 2 Air Fuel Ratio sensors and one Oxygen Sensor. The AF sensors are the two located closest to the engine. Also called upstream sensors, so 1 bank-one and 1 bank-two upstream AF ratio sensors.
The Oxygen sensor is located on the exhaust. It's also called the bank one downstream sensor. It is located under the driver's seat.
This information is for the 99 ES300. Earlier versions only had oxygen sensors, two upstream oxygen sensors and one downstream oxygen sensor.
Go here, http://www.densoautoparts.com/find-m...icle-selection to see what you need. Denso is the original equipment manufacturer of these sensors. If you need a sensor but a Denso.
Denso sells universal and an OE style sensors. The OE style is easier to install. The universal style requires the re-use of the electrical connector.
Last edited by tomf; 02-11-14 at 06:06 AM.
02-12-14, 01:54 AM
#22
Driver School Candidate
Thread Starter
Calc load (%) 37.3
ECT ( F) 176.0
STFT B1 (%) 0.8
LTFT B1 (%) 46.9
STFT B2 (%) 2.3
LTFT B2 (%) 51.6
Eng RPM 1717
Vehicle speed (mph) 38
IAT ( F) 100.4
Hope these numbers help. I also got this different list of about 22 but not sure how i did it on the scan tool.
02-12-14, 02:06 AM
#23
Driver School Candidate
Thread Starter
Thanks. I bookmarked that link you posted. I replaced 1 O2 sensor & 2 AF sensors but i was sold 2 of each so i ended up returning 1 extra O2 sensor because i only found 3 total. Based on your post i did replace each sensor correctly. But unfortunately this pesky P0171 emissions code still keeps triggering the check engine light. I have yet to throw in the towel!!! I shall discover and fix the root to this code. Satisfaction is long overdue.
02-20-14, 03:00 PM
#24
Driver School Candidate
Check the rubber boot that goes from the air cleaner to the throttle body for cracks. Especially around the ribs. That age and mileage the rubber gets old and brittle. If it is cracked then that can cause the P0171 also.
If thats not it I suspect its still your MAF.
I have a couple of questions about the emissions test you have to pass. Here in Texas, for that model its an OBD test where they check the computer for any codes. If its the same for you, how long did you drive the vehicle when you put a new MAF on it before retesting? I'm assuming you cleared the code but if the monitors didnt complete it will still fail.
If thats not it I suspect its still your MAF.
I have a couple of questions about the emissions test you have to pass. Here in Texas, for that model its an OBD test where they check the computer for any codes. If its the same for you, how long did you drive the vehicle when you put a new MAF on it before retesting? I'm assuming you cleared the code but if the monitors didnt complete it will still fail.
11-24-17, 11:06 AM
#25
Driver School Candidate
Thanks. I bookmarked that link you posted. I replaced 1 O2 sensor & 2 AF sensors but i was sold 2 of each so i ended up returning 1 extra O2 sensor because i only found 3 total. Based on your post i did replace each sensor correctly. But unfortunately this pesky P0171 emissions code still keeps triggering the check engine light. I have yet to throw in the towel!!! I shall discover and fix the root to this code. Satisfaction is long overdue.
01-25-20, 05:00 PM
#26
Had multiple codes.
Low coolant temp for closed loop, and too lean B1 upstream, then random misfires, then isolated to B2.
Changed B1 upstream AF sensor, lean condition went away, then still low coolant temp, then changed MAF, still there, then got ramdom misfires, not sure which cylinder or bank then it came up 2-4-6- changed VVTI Bank 2 sensor, need to drive to check if P300 code misfire goes away, also waiting for the ECT I bought to come in, since thiis might also throw the computer off.
Low coolant temp for closed loop, and too lean B1 upstream, then random misfires, then isolated to B2.
Changed B1 upstream AF sensor, lean condition went away, then still low coolant temp, then changed MAF, still there, then got ramdom misfires, not sure which cylinder or bank then it came up 2-4-6- changed VVTI Bank 2 sensor, need to drive to check if P300 code misfire goes away, also waiting for the ECT I bought to come in, since thiis might also throw the computer off.
Last edited by samsonn25; 01-25-20 at 06:04 PM.
01-25-20, 06:00 PM
#27
I changed the AF sensor and MAF and still have the 171. ECT is next as I already change VVTI on bank 2.
01-27-20, 05:43 AM
#28
Driver School Candidate
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samsonn25 (02-11-20)
02-11-20, 04:58 PM
#29
I finally disconnected battery for 10 min and reconnect and the car runs as good as before and OD is back.
Have code 1130 now.
I hear a small exhaust leak on passenger side, my theory is it causes the Af sensor and downstream O2 to read incorrectly, also possible it can trip the knock sensors which are 20 years old and make the computer enter limp home mode, thus the OD was gone earlier and now is back.
Put on a lift I hear the leak up somewhere between the exhaust manifold and Y pipe, not sure which connection
Have code 1130 now.
I hear a small exhaust leak on passenger side, my theory is it causes the Af sensor and downstream O2 to read incorrectly, also possible it can trip the knock sensors which are 20 years old and make the computer enter limp home mode, thus the OD was gone earlier and now is back.
Put on a lift I hear the leak up somewhere between the exhaust manifold and Y pipe, not sure which connection
02-17-20, 09:32 AM
#30
Driver School Candidate
I finally disconnected battery for 10 min and reconnect and the car runs as good as before and OD is back.
Have code 1130 now.
I hear a small exhaust leak on passenger side, my theory is it causes the Af sensor and downstream O2 to read incorrectly, also possible it can trip the knock sensors which are 20 years old and make the computer enter limp home mode, thus the OD was gone earlier and now is back.
Put on a lift I hear the leak up somewhere between the exhaust manifold and Y pipe, not sure which connection
Have code 1130 now.
I hear a small exhaust leak on passenger side, my theory is it causes the Af sensor and downstream O2 to read incorrectly, also possible it can trip the knock sensors which are 20 years old and make the computer enter limp home mode, thus the OD was gone earlier and now is back.
Put on a lift I hear the leak up somewhere between the exhaust manifold and Y pipe, not sure which connection