DTC 23: Operation Signal To Fuel Gauge
WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
Wait for 2 seconds after selecting DTC 23. If fuel gauge cycles from "F" to 1/2 to "E", resting on "F" in 2 second intervals, fuel gauge is okay. If fuel gauge movement is not as described, replace fuel gauge.