P0171 Mercedes-Benz -

Question

getting both codes..P0171B and P0174B....replaced both maf and filters and replaced the plugs too...code coming up also is P2187 and P2189 on 2008 cls 63..any suggestions? check engine light still coming on, but not right away.

Answer 1

P0171 and p0174 are codes for system to lean, meaning there is to much air 

purge control valve maybe.

you are OBD-II reader reads monitors, reset the check engine light and check monitors to see if the EVAP monitors complete.

 

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