I have the engine code P0171 on my 2003 Ford Focus

Question

I have a 2003 ford focus with a check engine code of po171. I have replaced both oxygen sensors and the ecm but the code keeps coming back on. Also when my car is running idle either in park or stopped at a light sometimes is just dies out, but it will start back up again. I would like to know what could be wrong.

Answer 1

Have you checked for intake leaks?

You can also try to clean the mass air flow sensor with mass air flow sensor cleaner.

you can check the resistance on the injectors. (see specs below)

if still no solutions use a fuel system cleaner the injectors might be clogged

 

 

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