Leaking or contaminated fuel injectors
Low fuel pressure or running out of fuel
Exhaust or intake air system leaks
Faulty Exhaust Gas Recirculation (EGR) system
Positive Crankcase Ventilation (PCV) system is leaking, or the valve is stuck open
Incorrectly seated engine oil dipstick, tube, or oil fill cap
Engine Light ON (or Service Engine Soon Warning Light)
Excessive Fuel Consumption
The Fuel Trim Cylinder Balance diagnostic detects a rich or lean cylinder to cylinder air/fuel ratio imbalance in each bank. The diagnostic monitors the pre-catalyst heated oxygen sensor (HO2S) signal’s frequency and amplitude characteristics by calculating an accumulated voltage over a predetermined sample period. An imbalance is indicated when multiple samples of the accumulated voltage are consistently higher than the desired value.
The Diagnostic Trouble Code (DTC) will be set when multiple samples of the pre-catalyst HO2S accumulated voltage are consistently greater than the desired value.