Brake pad wear
The amber brake-pad wear icon lights up when the sensor in a pad reaches critical thickness (2–3 mm of friction material). This is a 500–1500 km warning before a failure.
What this indicator means
The sensor is embedded in one pad (usually front). As material wears down, a metal contact touches the rotor — the circuit closes, and the ECU turns on the indicator. Some models (BMW, Mercedes, Audi) use electronic wear sensors with a separate alert.
Common causes
- Natural wear after 30–70k km
- Aggressive driving with hard braking
- Seized caliper — pad drags on the rotor
- False alert after pad replacement without adaptation reset
- Damaged sensor or broken wire
What to do as a driver
Visually inspect pads through the caliper cutout — friction thickness below 3 mm means replacement time. New pads cost $30–100 per axle. Do not push past 1000 km after the light appears — the metal backing plate starts scoring the rotor, and a $50 pad job becomes a $200–400 pad+rotor job.
Safety
Important: braking still works but efficiency drops. A metal grinding noise on braking means the friction material is gone entirely.