Q: I’ve begun hearing a faint squealing noise from my car — in the front, I think. It increases as I speed up and sometimes goes away if I use the brakes. With the holidays, this isn’t the best time for a car repair. Is it important that I fix this right away?

A: There’s a good chance the noise you’ve so nicely described is a brake-pad wear sensor beginning to sound off. These are little metal tabs attached to the inner brake pad that come into contact with the brake rotor when the pad’s friction material wears thin. While the nail on a blackboard sound will become increasingly annoying and embarrassing with further driving, the early warning of worn brake pads can head off some expensive damage. If a brake pad loses most or all of its friction material, its steel backing and/or the rivets attaching the friction material will cause severe damage to the brake rotor, along with decreased stopping ability.

Audible wear sensors are found on some but not all brake pads. Higher-end vehicles typically use an electrical sensor that illuminates a warning light when pad thickness significantly decreases, rather than subjecting the driver to an awkward sound. This probe-type of wear sensor requires replacement after activation for about $10-$40 apiece. Other warning light-type sensors are embedded within the brake pad, making replacement more straightforward.

A tab-type sensor can make noise in the way you described because brake pads ride just a hair away from the brake rotor, and flexing of both parts while driving or braking can cause intermittent contact. As your pads wear further, the noise will become louder and more continuous, to the point you won’t want to drive the car. The good news is you still have perhaps a month of driving remaining before this happens, and at least several more months of unimpaired brake operation.

If you’re considering a brief delay in having the brakes looked at, I’d feel better knowing the cause was in fact a wear sensor rather than something else that may require more immediate attention. Many wheels have sufficiently large gaps between the spokes to allow a nice view of the brake caliper and rotor. If so, the edge of the outer brake pad is usually visible if the wheel is rotated just right. Thickness of the friction material on a new brake pad is a bit greater than that of a pencil. If you see it’s less than one-third of this dimension, or if the gap between the pad’s metal backing and the rotor if the friction material isn’t visible, there’s a good chance a wear sensor is signaling or will be soon. Inner brake pads typically wear at a slightly greater rate than the outers, so a sort-of-thin outer pad means it’s time for brakes now.

Note: I received several reader inquiries regarding where to purchase brake fluid test strips. The strips I recommended are made by Phoenix Systems and are available in two quantities: a sample pack containing two for about $10 and a tube of 100 for about $67. You can find them at Walmart.com, eBay.com or Phoenix Systems’s own website, www.phoenixsystem.com.