What causes a car oxygen sensor to get dirty? What causes a car oxygen sensor to get dirty?
Regular use, age, lead and silicon contamination, soot buildup, oil leaks, muddy roads, and salt and water may cause a car oxygen sensor to get dirty. Oil into the engine may cover the probe, and cause it to malfunction. Silicon from grease or antifreeze compounds may contaminate the sensor with whitish-grayish deposits. Mixtures of oil, grease, and soot can cause of buildup of dark-colored residue. In short, chemical compounds and greases react to the heat that the engine produces, and when they are combined with other emissions from the engine, it results in buildup of soot and dirt around the probe and wires of the oxygen sensor.