When checking air gap on an ABS Wheel Speed Sensor, you should always use a brass feeler gauge to prevent the possibility of altering the magnetic properties of the tone ring. While not usually possible due to the design of most speed sensors, the air gap should be checked where possible. Only a few vehicles provide specifications for air gap with the range usually being from .020" to .070". Again, if in question, compare side to side and, if significantly different, check to see if the cause can be determined.
About the Author
Editor, Brake & Front End Magazine
Andrew Markel is an ASE Certified Technician and former service writer, and he brings this practical knowledge to the Brake & Front End team as editor.