The TPMS light means at least one tyre is 25% or more below its recommended pressure, OR a tyre pressure sensor has failed. Check all four tyres cold against the door-jamb sticker — a 2-minute top-up clears most cases.
Here's a quick, honest answer from a working UK mechanic — what causes it, what it costs to fix, and what to do next.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email bob@bobsmechanicalrepairs.co.uk.