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.
Consumption of certain foods, such as asparagus (which can impart a characteristic odor to urine), and taking some medications may be causes for changes in the odor of urine. The presence of bacteria in the urine, such as with a urinary tract infection (UTI), can affect the appearance and smell of urine. When there is an infection in the urinary tract, the urine may take on a foul-smelling odor as well as appear cloudy or bloody.