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Dear all
I have recently purchased a 2nd hand Passat GTE from 2017 August, with 100.000 km on the clock.

The car is driving fantastic and the brakes are rarely used due to the charging. However the discs are blue as if they have been overheated.

I can get new discs on the warranty but I am really puzzled about how this could happen, it it was one disc, hanging brakes would be the logical explanation, but it is both in front.

The discs are nice and polished despite the very rare use, however every morning when I reverse 10 meters to get out of the driveway I can hear that the brakes are activated.

So is there a Software feature that make sure that the brakes stay "alive" by activating them slightly from time to time e.g. a period after the car is turned on? And could it be this feature that is two aggressive and thereby result in overheating the brakes. (I have just driven 200.000 km in my old Passat which newer had a blue disc)

Looking forward to hear from you.

BR Rune
 

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I don't think there's any 'feature' in the car that activates the brakes for any kind of 'maintenance' purpose. The discs normally get little use in a GTE as you say. What I do to keep them 'clean' is when I leave home with a full battery I will leave the car in D mode for the first mile or so and brake late and heavy at the first couple of sets of traffic lights. This scrubs the discs clean so that I get nice quiet braking from there on (and use the discs very little because I normally drive in B mode). The car doesn't seem to attempt to do that kind of brake disc maintenance for itself as far as I've seen.
 

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Looking at your photo, the blue discs are likely to be an optical illusion caused by the blue caliper.

Seriously, if the discs have been overheated, because they are cast iron they will have microcracks rather than a "blue" steel appearance. If there are no cracks and no runout (vibration) problems, chances are all is good.
 

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If the battery is full when you lift off the accelerator the brakes should activate because there is nowhere for the regen to go so if you drive aggressively after fully charging the brakes should get a work out, I can hear the rust being removed on mine after it's been charging overnight and it's rained.

If your really worried get yourself a laser thermometer off Ebay go for a drive with minimal/no braking and check the disc temperatures all round, it should be obvious if they are overheating.

Your discs look to be in good condition, no visible sign of a lip which would indicate a lot of use, measure the pads so you can keep an eye on the wear rate.

All looks good in the hood to me.
 

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It’s probably had corrosion on the discs at some point, that will cause it to be discoloured. With a full battery the mechanical brakes will still work at very low speeds as the motor cannot give you any braking.
 

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They do look like they've experienced high temperatures recently...

The obvious thing to check would be whether the caliper has seized? If it's permanently dragging then you'll get an overheating this way, and with how little brakes get used on EVs they are more prone to seizing than on an ICE.

Is it the same on both sides?
 

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If your really worried get yourself a laser thermometer off Ebay go for a drive with minimal/no braking and check the disc temperatures all round, it should be obvious if they are overheating.
You can do the same thing with your finger, if it hurts a lot you've got a problem ;)
 

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With 100.000 km in the clock it seems that it has been imported, so with the higher temperatures on the continent may explain the overheated discs.
 
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