Can't find a leak on 2002 Toyota tundra with P0171

codes are OBDll and are available online free
P0174

• Intake air leaks
• Faulty front heated oxygen sensor
• Ignition misfiring
• Faulty fuel injectors
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Faulty Mass Air Flow (MAF) sensor
• Incorrect Positive Crankcase Ventilation (PCV) hose connection
• P0171
• Intake air leaks
• Faulty front heated oxygen sensor
• Ignition misfiring
• Faulty fuel injectors
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Faulty Mass Air Flow (MAF) sensor
• Incorrect Positive Crankcase Ventilation (PCV) hose connection
• P0102
• copy and paste
• https://www.justanswer.com/ford/2dnqt-98-windstar-dtc-p0102-sitting-trouble-code-mil.html

copy and paste
https://www.justanswer.com/ford/8kg47-ford-windstar-code-p0302-p0305.html

P0453
copy and paste
https://www.justanswer.com/ford/3qxa3-getting-po453-code-evap-pres-sensor-high-99-windstar.html

Air/Fuel Mixture System Lean Bank 1

- Intake air leaks (vacuum leak somwhere)
- Faulty front heated oxygen sensor
- Ignition misfiring - coil, igniton module, distributer malfunction
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure- fuel filter or weak pump
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection
or bad pcv valve.

******************* most likely vacuum leak

P0171 FORD - Fuel Injection System Too Lean Bank 1http://engine-codes.com/p0171_ford.htmlForum CodePossible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection Tech notes 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 replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced

P0171 - System Too Lean Bank 1
Possible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection Tech notes 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 replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.

P0171 JAGUAR - System Too Lean ENGINE CYLINDER Bank 1 (only "V" engines (V6,V8 etc.) have more than one bank of cylinders.

Possible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection Tech notes 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 replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.

P0171 HYUNDAI - System Too Lean Bank 1

Possible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection

P0171 VOLKSWAGEN - System Too Lean engine cylinder Bank 1
Possible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection
P0455 VOLKSWAGEN - EVAP System (fuel vapor storage and control) Large Leak Detected
Possible causes- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking

P0171 AND P0174
P0171 - System Too Engine Cylinder Lean Bank 1http://engine-codes.com/p0171.htmlForum CodePossible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection Tech notes Dirty air filter of faulty air flow sensor are common causes for the P0171 code of the problem.


P0174 FORD - Fuel Injection System Too Lean Bank 2http://engine-codes.com/p0174_ford.htmlForum CodePossible causes- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection Tech notes The codes is usually set when there is an intake leak after the air flow meter, before replacing any parts check for loose or broken hoses and intake gasket leak. On Ford some models dirty air filter, and dirty or faulty air flow sensor are the cause of the problem.

P0171 Symptoms
Bank 1 O2 sensor Indicates always lean - Engine Light ON (or Service Engine Soon Warning Light)
- Excessive Fuel Consumption Possible causes - Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection

p0171 is system to lean ( bank 1 ). did you turn off check engine light with a scanner! if not go to auto-zone and they will erase it for free, then you can see if light stays off. There could be a vacuum leak downstream of the MAF sensor.

Inspect all vacuum and PCV hoses, replace if necessary

Check for a dirty fuel filter and proper fuel pressure. 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. good-day!!