Make/model/year of car?
Had a few Vectras with this, ham-fisted dolts changing brake pads without clamping brake hose, flipped seals in the ABS unit, needed new ABS unit.
I take it you are not losing brake fluid as this would, obviously, point to a leak in the system.
Has the system been bled correctly? Best to activate the ABS pump using Tech-2 or similar while pressure bleeding to do the job properly.
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