A loop sensor is cut by the disc when the pad wears down, opening a circuit. A continuous sensor changes resistance progressively as it wears away.

The loop type is a wire embedded in a plastic tip that sits in the pad at the trigger depth. Contact with the disc severs it.

That gives one binary warning and destroys the sensor, so it is a consumable.

A continuous sensor uses a resistive track that shortens as it abrades, so the resistance the vehicle reads maps to remaining thickness.

That allows a percentage or distance-remaining readout and is common on commercial vehicles where planning the workshop visit matters.

Some designs give two stages - an early advisory and a final warning - which is the practical middle ground.

A triggered loop sensor always. An untriggered one can be reused if it is undamaged, though most kits include new ones.

Once the loop is cut the sensor has done its only job and cannot warn again.

If the pads are changed before the sensor triggers, the sensor is often physically fine - but it has been through the same heat cycles and its cable and connector have aged.

Given the cost relative to the labour of returning to the job, fitting new sensors is the sensible default.

Continuous sensors are sometimes designed to be reused until fully worn, so check the manufacturer's guidance rather than assuming.

Never reconnect a cut loop or bridge the connector. It clears the lamp and removes the warning for the next set of pads.

Often not. Many vehicles fit sensors only on the axle that wears fastest, so an unlit warning lamp does not mean every corner is healthy.

Fitting sensors at every corner costs more and is not always judged necessary by the manufacturer.

Front-only monitoring is common on vehicles where the front brakes do most of the work.

Some vehicles monitor one wheel per axle rather than both, which assumes even wear - an assumption a sticking caliper breaks.

Anyone writing an inspection schedule needs to know which corners are monitored on each platform, because the unmonitored ones still need measuring.

Treat the warning lamp as a prompt to inspect everything, not as a report on the corner it came from.

Usually a damaged cable or a corroded connector, because both produce the same open circuit as a worn-out pad.

The sensor cable runs through one of the harshest areas on the vehicle: heat, water, salt and suspension movement.

Chafing where the cable passes a bracket or a suspension component is the commonest cause, and it is easy to create during a pad change by routing the cable badly.

Corroded connectors give intermittent faults that come and go with vibration and moisture.

Check continuity at the sensor before condemning anything, and inspect the whole run rather than just the ends.

Route the new cable exactly as the original was, using the clips provided - a sensor cable pulled tight by suspension travel will fail within weeks.

Yes, and few maintenance signals are more useful - particularly with continuous sensors that report remaining life.

Progressive sensors let telematics report remaining friction as a percentage, so brake work can be scheduled with other planned maintenance.

That converts an unplanned off-road event into a booked workshop slot, which is where most of the value is.

Wear rates by vehicle and by driver expose duty and driving-style differences that no other single measurement shows as clearly.

A corner wearing far faster than its opposite number is a sticking caliper reported automatically, before it damages the disc.

The data is only as good as the sensor coverage, so record which corners each platform monitors alongside the readings.

Only where the pads have a sensor slot and the vehicle has the wiring and the warning circuit - otherwise a standalone monitoring system is the alternative.

The pad itself must be the version with a sensor pocket, and not every pad in a range is.

The vehicle needs a circuit that does something with the signal. Without an instrument-cluster input, the sensor has nowhere to report to.

Aftermarket standalone monitors exist that read the sensors and drive their own warning lamp or telematics input, which suits mixed fleets.

On heavy vehicles, retrofit systems that measure pad thickness or chamber stroke directly are more common than pad-embedded sensors.

Weigh it against the alternative: a disciplined inspection schedule with recorded thicknesses achieves much of the same result with no hardware at all.

No. Length, connector, trigger depth and electrical behaviour are all vehicle-specific, and a mismatched sensor warns at the wrong point or not at all.

Cable length and routing are designed around one vehicle's suspension travel, and a short cable will be pulled apart.

Connectors differ physically and are not adaptable safely, because the joint sits in a wet, salty environment.

Trigger depth is set to the pad's own minimum thickness, so a sensor from a different pad warns too early or dangerously late.

Continuous sensors are calibrated to the vehicle's expected resistance range, and a substitute simply reads wrong.

Order by vehicle rather than by appearance, and expect the correct sensor to be supplied with a quality pad kit for platforms that use one.