An ABS warning light that comes on, then goes off, then returns is one of the trickier brake-electronics symptoms - intermittent faults are harder to pin down than steady ones. But the causes are a short list. Here is what makes the ABS light flicker.
An intermittent wheel-speed sensor
The most common cause is a wheel-speed sensor reading erratically - see what is a wheel speed sensor. A sensor with a cracked tip, a bit of metal debris on it, or a damaged tone ring may read fine sometimes and drop out over bumps or at certain speeds, tripping the ABS light then clearing. This on-off pattern is classic for a failing sensor.
Wiring and connectors
A chafed wire or corroded connector at a wheel sensor flexes with the suspension, making and breaking the connection intermittently. Salt and moisture in a connector cause the same come-and-go fault. Because the wires live in a harsh environment, wiring issues are a frequent cause of a flickering ABS light - see how ABS works.
Low voltage or a stored glitch
A weak battery, bad ground, or a recent electrical event can make the light appear then clear - see ABS light after battery change. If it started after battery work, check the terminals and charge first. A one-time glitch may not return.
How to find it
Intermittent faults are best caught with a scan tool that logs the code even after the light clears, pointing to the exact wheel. Clean or replace the suspect sensor, repair wiring, and confirm. Your normal brakes still work with the light on, but fix it to restore ABS. Keep the brakes healthy with quality pads and hardware.