What’s the Difference Between Wide Band and Narrow Band Air/Fuel Meters

Wide Band Shows Actual Air/Fuel ratio. Precise display of ratio on the rich side of “stoichiometric”, which is where all performance engines run. Usually displays Air /Fuel ratio to the second decimal place. Useful for maximizing power from race and other performance engines. Fully temperature compensated. Higher cost.

Narrow Band Shows indication of rich vs lean. Usually has very “coarse” display of ratio on the rich side of “stoichiometric. Some units only have 2 LEDs for the entire rich range! Really only useful for making sure your engine is not running on the lean side. Usually not temperature compensated, so the same air/fuel condition in the motor will result in an indication on the meter that will vary depending on sensor temperature. Low cost.

Bottom Line:

If you are a builder or tuner of performance engines who needs to maximize performance of the engines you work with, then you need to be measuring Air/Fuel ratio with a wide band meter.
If you simply want an indication that you are rich or lean to make sure you are not going to burn the motor up, you can get by with a narrow band meter.