Question about 2003 Chevrolet Impala

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How do i determine which 02 sensor is defective? i've gotten a p0171 dtc and im not sure which sensor should be replaced

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  • james bierman Sep 11, 2010

    po171 is not neccesarly a bad o2 sensor

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P0171 is not a defective sensor, it is the bank 1 (irrelivant) senor that has sensed a lean mixture... in other words too much oxygen in the exhaust.
This is usually a MAFS or MAP fault but it can be a leaking inlet gasket or simply a vac pipe disconnected.

Dony change an o2 sensor, they are working fine

Posted on Sep 11, 2010

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I have a PO171 code on my 1999 Jeep grand cherakee larado can You tell me how to fix it, Thank You.


  • Dale, code P0171 fuel system too lean
  • Possible causes
  • change fuel filter first, if it has not been done recently
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SENSOR
O2 SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
O2 SENSOR HEATER OPERATION
TPS VOLTAGE GREATER THAN 0.92 VOLTS WITH THROTTLE CLOSED
TP SENSOR SWEEP
MAP SENSOR OPERATION
ECT SENSOR OPERATION
ENGINE MECHANICAL PROBLEM
FUEL FILTER/PRESSURE REGULATOR (HIGH)
PCM
Check the attached links,
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

2000 Jeep Grand Cherokee p0171

Possible problems related to Code P0171 Jeep Garage Jeep Forum

P0171 System to Lean Bank 1

Code P0171

Mar 11, 2016 | Cars & Trucks

1 Answer

Dtc fail code P0171 and then p2004


a po 171 is a bad 02 sensor

Mar 03, 2012 | Ford Cars & Trucks

1 Answer

Im throwing code p0171 bank 1 system too lean changed plugs fuel filter cleaned maf sensor swapped bank1 and bank 2 upstream 02 sensor to c if code red diff but it didnt and sprayed carb cleaner all over...


Your problem is the mass air flow sensor is bad theat code is miss leading a p0171 and p0174 are both miss leading replace the mass air flow sensor and clear the codes.

May 10, 2011 | GMC Sierra 1500 Cars & Trucks

2 Answers

Code p0171 system too lean bank 1


I could be wrong but that sounds like maybe an oxygen sensor (bank 1). Not sure what code i had on my car but the only bank 1 and bank 2 I heard of is the oxygen sensor but you can always go to autozone and they can check the code and tell you what it is.

Mar 03, 2011 | Buick Century Cars & Trucks

2 Answers

Engine light code p171 comes up. I recently changed the air flow sensor. Everything else is working fine. What can this be in a Toyota Corolla 2003?


DTC P0171 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
1. Exhaust system leak.
2. Improper fuel pressure.
3. Fuel injector restricted.
4. Defective heated oxygen sensor No. 1.
5. Defective Manifold Absolute Pressure (MAP) sensor.
6. Defective Engine Coolant Temperature (ECT) sensor.

System Too Lean. This code will set when an air fuel ratio sensor (O2 sensor) gets lazy.

Also, check for a vacuum leak on that side.



Jan 26, 2011 | 2003 Toyota Corolla

1 Answer

I have a scion tc 05 with this code p171 . what does it mean?


DTC P0171 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
1. Exhaust system leak.
2. Improper fuel pressure.
3. Fuel injector restricted.
4. Defective heated oxygen sensor No. 1.
5. Defective Manifold Absolute Pressure (MAP) sensor.
6. Defective Engine Coolant Temperature (ECT) sensor.
When the air fuel ratio feedback is stable after the engine is at operating temperature and the fuel trim has reached its limit of correction to the rich side. (2 trip logic).
Feedback from the HO 2 sensor influences short-term fuel trim and short-term fuel trim influences long trim fuel trim. Short-term values are temporary and not stored when the ignition key is turned off. Long-term values are stored in memory because they are part of the basic injection duration. Long term values affect injection duration in closed and open loop because they are used to calculate basic injection duration. It is important to remember that the actual fuel trim will be the opposite of the DTC. A system too lean, DTC P0171 will mean the ECM is making a + or rich correction.
read (and let me know)above data and Freeze Frame by using (example, generic) Scan Tool on # mode 2, etc.
Slowly accelerate the engine in the increments shown and record voltage,
grams/sec of MAF and SFT, LFT, Injection Pulse, Fuel Pressure, etc.
HTH,
Vehicle have MAF Sensor?

Jan 03, 2011 | 2001 Toyota Corolla

1 Answer

I have a 1997 Chevy Blazer with the 4.3 engine. The Service Engine light keeps coming on. I scanned the codes and replaced the O2 sensor just before the catalytic converter. The light is still coming on...


P0146 pd means pending code
Pending codes and DTCs? Posted on November 12, 2010 by fcrmaster
When reading codes from your vehicle the fault code reader may show them as pending codes or normal Diagnostic Trouble Codes (DTC).
Pending codes (also known as continuous monitor codes) will be registered when an intermittent fault occurs. If that fault does not happen again after x number of start/stop cycles, the ECU will erase the code from memory. If the fault is persistent it becomes a DTC.
If you have read pending codes it is advisable to check the codes again after a week or so. If there is no apparent problem with the vehicle it is safe to erase the codes too and check back. But always make a note of any fault codes with the date and mileage of a vehicle.
If the codes read include a DTC then you need to investigate further. This you can either do yourself or advise your garage. If, again, you don't see an apparent problem (depending n the severity of the code) with the vehicle you can note the codes down and erase them. Then check again after a week or a few days depending on how often the vehicle gets used. If a repair has been made (previous owner) the DTC may just not have been reset after the repair.
The other numbers behind the code 01/06 , 02/06, 03/06 , 05/06 ,04/06 These don't mean anything . cheap code reader .
DTC P0140 HO2S Circuit Insufficient Activity Sensor 2
DTC P0146 HO2S Circuit Insufficient Activity Bank 1 Sensor 3
DTC P0171 Fuel Trim System Lean Bank 1
DTC P0174 Fuel Trim System Lean Bank 2
Sorry but this is something you should take to a qualified repair shop that has a diagnostic tool that can view sensor scan data.
Causes of lean condition trouble codes P0171 P0174 GM 5 3L

Jul 23, 2017 | 1999 Chevrolet Camaro

1 Answer

Emissions egr came up on the computer test i replace it now oxygen sensor are coming up its has 4


a defective EGR valve will at time effect 02 sensor functions. But even though you vehicle does have 4 02 sensor. The DTC (diagnostic trouble code) will indicate which 02 sensor is faulty. ask the tech who performed the test on your vehicle to tell you which sensor has malfunctioned. or get the dtc code from him then google the dtc for your vehicle and you will have the answer to your question

Mar 21, 2010 | Ford Windstar Cars & Trucks

1 Answer

Ford windstar check engine light comes on after stopping when starting to get moving again shows p0171 & p0174 codes why??


P0171 indicates a lean condition. The most common cause of this is a defective mass air flow sensor. Also check if any vacuum leaks. P0174 OBD-II Trouble Code


Technical Description

System Too Lean (Bank 2)


What does that mean?

Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust.

Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.

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Thanks.


Dec 17, 2009 | 2002 Ford Windstar Cargo

2 Answers

P0171 just change the mass air flow light came on


Hi,

Volvo's code - P0171 means: Long-term fuel trim, part load. Long-term fuel trim, idling.

You will need to refer to a workshop manual, to ascertain the correct inspection procedure.

Cheers,

Nov 05, 2009 | 2001 Volvo S60

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