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OBD-II · Motor och drivlina (P)

P0174

System too lean bank 2

Vad den betyder

Bank 2 is running with too much air or not enough fuel.

Symtom

  • engine warning light
  • hesitation or flat spots when accelerating
  • rough or hunting idle, sometimes stalling
  • may be worse when cold or at idle

Troliga orsaker, den vanligaste först

Troliga orsaker, den vanligaste först
No.Orsak
01vacuum leak, often a failed crankcase breather (PCV) valve or split intake hose
02dirty or failing MAF sensor under-reading air flow
03low fuel pressure (weak pump, clogged filter)
04exhaust leak before the bank 2 lambda sensor
05LPG system running lean on converted cars

Vad du ska kontrollera, steg för steg

  1. 01Read short- and long-term fuel trims at idle and at about 2,500 rpm: high trims at idle that improve with rpm point to a vacuum leak; high trims at all speeds point to fuel delivery or the MAF
  2. 02Smoke-test the intake and check the crankcase breather/PCV valve (a whistle or strong suction at the oil filler cap is a clue)
  3. 03Compare MAF readings with OEM values; clean only if permitted by the sensor maker, otherwise replace a confirmed faulty sensor.
  4. 04Check fuel pressure and delivery (pump, filter)
  5. 05On LPG-converted cars, check whether the trims are normal on petrol; if so, service or recalibrate the gas system
  6. 06Check for exhaust leaks before the upstream lambda sensor