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.
Causes. Urine odor is related to the volume and concentration of a variety of substances excreted by the kidneys. Normally, urine that contains a lot of water has little to no odor. If your urine becomes highly concentrated â a high level of waste products with little water â urine odor may have a strong ammonia smell. Many foods and medications, such as asparagus or certain vitamins, can affect the odor of urine. Sometimes, unusual urine odor may indicate a medical condition or disease, such as: 1  Bladder infection. 2  Cystitis (bladder inflammation). 3  Dehydration. 4  Diabetic ketoacidosis (high levels of blood acids called ketones). 5  Gastrointestinal-bladder fistula (abnormal connection between the intestines and bladder).