My car keeps on throwing a code P0171 Too Lean..?

Question

Car keeps on throwing a code P 0171 Too lean, I have changed the fuel filter in the off chance that was it but the problem still remains. Does anyone have any idea if it is a sensor or what else it could be? I was thinking maybe the O2 sensor but I don't know.

Answer 1

It could be a sensor or the computer, but those are kind of catchall explanations which can apply to almost anything.  Have you checked the fuel pump and injectors?

Answer 2

lol who told you it was the o2 sensor auto zone? what kind of car or truck is it. get it smoked at a shop and see where its leaking. its most likely the intake gasket but could be the maf. this is a code that cant be diagnosed without  proper diagnostic equipment including a smoker and a scanner.

Answer 3

Start by checking for a vacuum leak. Pay special attention to the hose for the pcv. They get oil soaked and start leaking.

It's probably not the O2 senser. That just tells the computer what the combustion is doing.

Don't shoot the messenger.

The type of vehicle would help also.

Answer 4

P0171

Fuel trim bank one condition

   – The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

Probable Cause[s]

   1. If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) Sensor

   2. Oxygen sensor defective

   3. Ignition misfire-repair

   4. Fuel injector problem

P0171 Honda

Fuel System Too Lean Bank 1

   –

Probable Cause[s]

   1. Large vacuum leak

   2. Fuel system concern

   3. Ignition system concern

   4. MAF sensor faulty

   5. HO2S/AF Ratio Sensor Fault

P0171 Infiniti

Fuel Injection System Too Lean- Bank 1

   –

Probable Cause[s]

   1. Low fuel pressure or restricted flow

   2. Ignition system fault

   3. Large vacuum leak

   4. Faulty MAF sensor

P0171 Kia

Bank 1 System Too Lean

   –

Probable Cause[s]

   1. Large vacuum leak

   2. Faulty fuel injector

   3. Fuel system fault

   4. Ignition system fault

P0171 Lexus

System Too Lean Bank 1

   –

Probable Cause[s]

   1. Lean air/fuel ratio-Fuel injector or vacuum leak

   2. MAF Sensor concern

   3. ECT Sensor fault

   4. Faulty HO2S

P0171 Mazda

Lean air/fuel ratio bank 1

   –

Probable Cause[s]

   1. Low fuel pressure

   2. Large vacuum leak

   3. Dirty/defective MAF sensor

   4. Engine mechanical condition

P0171 Mitsubishi

System Too Lean- Cylinders 1-4

   –

Probable Cause[s]

   1. Ignition system faulty

   2. Fuel system faulty- Injectors or pressure

   3. Vacuum leak

   4. Engine mechnical condition

P0171 Nissan

Fuel system lean bank 1

   –

Probable Cause[s]

   1. Low fuel pressure

   2. Blocked injector(s)

   3. Large vacuum leak

   4. MAF sensor fault

P0171 Subaru

System Too Lean- Bank 1

   –

Probable Cause[s]

   1. Faulty MAF Sensor

   2. Large vacuum leak

   3. Low fuel pressure

   4. Plugged injector or cylinder misfire

P0171 Toyota

Air/fuel mixture system lean bank 1

   –

Probable Cause[s]

   1. Low fuel pressure

   2. Faulty MAF/VAF sensor

   3. Cylinder misfire condition

   4. Faulty HO2S/AF sensor

   5. Large vacuum leak

P0171 Volkswagen

System Too Lean Bank 1

   – Low fuel pressure or volume

Probable Cause[s]

   1. Faulty HO2S

   2. Large vacuum leak

   3. Faulty MAF Sensor