Technician A says a loose oil filler cap or a dip stick that is not fully seated in the dipstick tube can change the LTFT on a MAF system. Technician B says the PCV system will draw unfiltered air through these leaks which could result in premature wear of engine parts. Who is correct?

Question

Quizplus · Accepted Answer

Both technicians are correct. A loose oil filler cap or a dipstick that is not fully seated can indeed allow unmetered air to enter the engine, affecting the Long Term Fuel Trim (LTFT) in a Mass Air Flow (MAF) system as mentioned by Technician A. Technician B is also correct in stating that the Positive Crankcase Ventilation (PCV) system can draw unfiltered air through these openings, potentially leading to premature wear of engine components due to contaminants entering the engine.

Technician a Says a Loose Oil Filler Cap or a Dip