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P0171 2011 FORD FOCUS

P0171 2011 FORD FOCUS - System Too Lean Bank 1

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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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 replace the air filter and clean the air flow meter. If the problem persists the front oxygen (O2) sensor may need to be replaced.

When is the code detected?

- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Excessive Fuel Consumption

P0171 2011 Ford Focus Description

The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit.
OBDII Code P0171 2011 Ford Focus - System Too Lean Bank 1 - AutoCodes.com

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Related Information

P0171 2011 FORD FOCUS Comments

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