How do I know if my car has warning for worn our brake pads? Does it need to have a sensor of some kind?

There is an electrical lead / connector attached to the inner brake pad on the front nearside brake assembly.

 

When the pads wear down to a certain level there is a metallic element that is exposed, completing a circuit and bringing on the dash warning.

 

If you're reasonably flexible you can squeeze your head behind the wheel or slide under the car to take a look.

 

Here are the old pads I removed from my MkII Superb showing the electrical connector...

 

 

Edited 29 October, 20196 yr by silver1011

So not every car has that? What happens if you continue driving with brake pads worn out too much?

Edited 29 October, 20196 yr by toni8b

1 hour ago, toni8b said:

So not every car has that? What happens if you continue driving with brake pads worn out too much?

 

You run the risk of damaging the discs, failing your mot or having an accident and potentially killing someone, if not yourself.

Or, more often, just a nasty screeching noise and slightly less effective brakes.

The noise will make you need to address the problem promptly.

10 hours ago, tunedude said:

 

You run the risk of damaging the discs, failing your mot or having an accident and potentially killing someone, if not yourself.

Of course, but that makes me wonder why would a car not have sensor for this warning..?

 

I will see if my head fits between the tyre and the wheel arch.

Edited 30 October, 20196 yr by toni8b

17 minutes ago, toni8b said:

Of course, but that makes me wonder why would a car not have sensor for this warning..?

 

I will see if my head fits between the tyre and the wheel arch.

Because I change my alloys/tyres twice a year, simply jack the car up and remove a wheel and it is easy to see how much meat is left on the brake pads.

And the main dealer checked mine as 20% worn at 34,000 miles. Without taking the wheels off.

Not all cars have such warnings. Iirc some pads had brass pins embedded to make an aural warning before the steel back plates made contact. I'd a Renault 18 in the early 1980s with electrical wear indicators. The coating of salt in Buxton winters completed the circuit frequently. 

 

Edited 30 October, 20196 yr by gregoir

2 hours ago, toni8b said:

Of course, but that makes me wonder why would a car not have sensor for this warning..?

 

Cost…. VAG produce around 10 million vehicles a year...

If the sensor costs €1, that's a substantial saving to be had from removing it & putting in the handbook "check your brake pads regularly"...

10 minutes ago, Gabbo said:

 

Cost…. VAG produce around 10 million vehicles a year...

If the sensor costs €1, that's a substantial saving to be had from removing it & putting in the handbook "check your brake pads regularly"...

On the subject of the VAG they released figures today for the first 9 months of 2019trading and of the 7,500,000 vehicles sold so far upto the end of September their pre-tax profit was $16.4 BILLION. Not worked out the average per car but must be quite nice.

Cars are a ludicrous mark up - I work for an interior acoustics (carpets etc) manufacturer that supply parts for a well known Japanese SUV.  We sell them something like a wheel arch liner for literally pence per unit....bet they're nothing short of £20-30 a piece from the main stealer for service parts!

9 hours ago, toni8b said:

Of course, but that makes me wonder why would a car not have sensor for this warning..?

 

Because it's not really needed tbh.

I've never had one and it's never been a problem.  Regular serving highlights wear, whether that's DIY or paid for.

Worst case it'll be an advisory on an MOT when they get lowish and ultimately fail when it gets really low...  I forget the limits.

 

Usually pads have squeal clips on too.

2 hours ago, Alex-W said:

 

Because it's not really needed tbh.

I've never had one and it's never been a problem.  Regular serving highlights wear, whether that's DIY or paid for.

Worst case it'll be an advisory on an MOT when they get lowish and ultimately fail when it gets really low...  I forget the limits.

 

Usually pads have squeal clips on too.

The MOT has a changed a bit on brake pad wear, the change came in on the 01/05/2018, two types of fail now,

 

1) Brake pads worn below limit-Dangerous, the limit is 1.5mm or the Thickness of a 5p coin

2) Brake pads worn down to wear indicator-Major, exactly what it says if the pads are worn down to the wear indicator (not electrical contact type but the small metal type the makes a noise) the the brake pads will fail.

 

The majority of vehicles now have some kind of wear indicator fitted to them.

 

Believe it not 48 tonne lorry's have the same limits. Yep i know shocking.

Edited 30 October, 20196 yr by Ju1ian1001

They usually put on an advisory way before that though...  I've had it flagged on mine when there's about 5mm left.

1 minute ago, Alex-W said:

They usually put on an advisory way before that though...  I've had it flagged on mine when there's about 5mm left.

Us testers do try to, i normally advise brake pads at about 4mm as the wear indicators are normally set for 2.5mm of pad meterial  left.