A brake caliper does not have to seize completely to cause trouble. A piston, slider or handbrake mechanism can begin to bind, leaving one brake partially applied after the pedal is released.
What the driver may notice
The car may pull, feel reluctant to roll or use more fuel. There can be a hot smell after a short journey, more dust on one wheel or one side becoming noticeably hotter than the others. In other cases the only clue is uneven pad wear discovered during servicing.
Why it happens
Moisture and corrosion can affect the piston surface or sliders. A damaged dust boot lets contamination enter. Flexible brake hoses can also fail internally and act like a one-way restriction, allowing pressure into the caliper but slowing its release.
Heat changes everything
A binding brake generates heat continuously. That can damage the disc, pads, bearing, seals and brake fluid. The symptom may become worse as components expand, then appear to disappear after the vehicle cools.
Repair or replace?
Cleaning and lubricating serviceable sliders may be appropriate when the parts are otherwise sound. A corroded piston, damaged bore, failed integrated mechanism or contaminated friction material usually needs more extensive repair or replacement. Both sides should be inspected, but parts are not automatically replaced in pairs without considering condition and manufacturer guidance.
If a wheel is extremely hot, smoke is visible or the vehicle pulls strongly, stop driving. Book a brake inspection in Ruislip before the fault causes further damage.
Still not sure what is causing the problem?
Symptoms can overlap between several faults. A proper inspection and diagnostic process is usually cheaper than replacing parts based on guesswork.