Defective ignition coil(s) Bad spark plug(s), spark plug wires, or spark plug boots. Faulty fuel injector(s) Malfunctioning fuel delivery system (fuel pump, fuel pump relay, fuel injectors, or fuel filter) Major engine vacuum leak. EGR valve stuck in the wide open position. Clogged EGR ports.
The following conditions can sometimes cause smelly urine, but they are uncommon: 1  urinary stones â these may cause an ammonia-like odour (read about bladder stones and kidney stones) 2  a bladder fistula â this is an abnormal connection between your intestines and bladder.
Most of the time, urine does not have a strong smell if you are healthy and drink plenty of fluids. Most changes in urine odor are not a sign of disease and go away in time. Some foods and medicines, including vitamins, may affect your urine's odor. For example, eating asparagus causes a distinct urine odor. Foul-smelling urine may be due to bacteria. Sweet-smelling urine may be a sign of uncontrolled diabetes or a rare disease of metabolism. Liver disease and certain metabolic disorders may cause musty-smelling urine. Some conditions that can cause changes in urine odor include: Bladder fistula.