I have a 1997 nissan sentra that wi have a 1997 nissan sentra that wont pass emisions fuil system lean bank1 p0171 code so i changed the maf sensior,fuil pressure reg, pcv valve, and all four fuil injectors, now the car has no power at all it hardly move now with pedle to the floor it wont go can any body help me please. ont pass emisions fuil system lean bank1 p0171 code so i changed the maf sensior,fuil pressure reg, pcv valve, and all four fuil injectors, now the car has no power at all it hardly move now with pedle to the floor it wont go can any body help me please.

Sometimes this is NOT a O/2 sensor issue ,,,,,If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.
The P0171 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate,,,,,

p0171 refers to system too lean bank 1 causes ---intake /exhaust leak AIR system---MAF/VAF sensor---fuel pressure/pump---injector/s -- HO2s .==check the flexible section of the exhaust at the manifold for cracks -check the hos2 sensor==have a pressure test done on the fuel manifold.

PO171- System too lean (Bank1)

Most likely a failed oxygen sensor on the passenger side,
if you never changed the front or upstream sensors at 100,000
miles, as preventative maintenance

Do both sides,clear codes & if they come back, check for vacuum leaks

Do spark plugs every 3 years, as well as fuel & air filter

Spray throttle body inlet with CRC Throttle Body Cleaner

Spray MAF Sensor with CRC MAF Cleaner

Check Fuel Pressure a rail port with a gauge (38# to 42# )

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.

P0171 : System too lean (Bank1) .

This problem is usually caused by a dirty (MAF ) Mass AIR Flow sensor. Did you notice any change with your car drivability ? Good luck

hola mi nombre es victor y tengo un nissan sentra y stoy tratando de pasarle emicion pero cuando voy para motor beiculos el carro ensendio un chec engine y me *** los codigos p0134 p0325 p0171 si tiene alguna idea que puede ser mi numero de telefono es 2039790930 y mi correo es [email protected]

P0171 - Fuel Trim, Bank1 System too Lean
VW DTC 16555 (P0171) - Fuel Trim, Bank1 System too Lean
By only pulling battery power from the ECU doesn't clear the codes on OBDII systems.
You must have access to a VAS, VAG-COM, Bosch KTS, ... diagnostic scantool. The ECU (Electronic Control Unit for engine management) is seeing a fuel trim that's much too lean even with the ECU making adjustments. Colud be the MAF (Mass Air Flow) sender out of order, the pre-cat O2 sensor, or a significant vacuum leak. You need to confirm / deny working parts with a 2nd gear pull data-logging measuring blocks 002, + 032 (VAS, VAG-COM).

P0171 - System Too Lean (Bank 1) indicates a bad reading from an O2 sensor or bad MAF sensor.
CausesA 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 may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
• There could be a vacuum leak downstream of the MAF sensor.

Possible SolutionsPossible 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

do you mean P0171??
If so, then it means your MAF sensor may be dirty and needs to either be cleaned or replaced.
It could also mean there's a vacuum leak downstream of the MAF sensor

Hi
171 system too lean
174 system too lean
2195 - 02 ozygen sensor signal stuck lean Bank1 Sensor 1
2197- 02 ozygen sensor signal stuck lean Bank 2
Sensor 1
The 2 front 02 sensors are located on the front of
the exhaust manifold.
Should solve problem and increase gas mileage.