p0171 on 2005 chevy cobalt ss sc 2.0l.

Question

changed air filter, replaced cracked intake hose, car runs perfect, check what next?

Answer 1

P0128 Engine Coolant Temperature Below Thermostat Regulating Temperature. I think the thermostat maybe be getting stuck
 

P0171  Fuel Trim System Lean Bank 1- try to clean the mass air flow sensor with mass air flow sensor cleaner. if it does not help check fuel pressure.

 

- 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