Audi Q8 Brake Warning Light: Why is it on?
Your Audi Q8‘s brake light indicator is there to let you know that there is an issue with the brake system. It is different than the anti-lock brake system, which gets its own ABS warning light. The brake light indicates that there is a problem with the physical braking system itself.
If you are reading this article trying to figure out whether you should drive your vehicle, check the emergency brake first. If it’s engaged, the brake light will stay lit. If the handle isn’t all of the way down, it’ll cause the brake warning light to stay on. Check to make sure that there isn’t the little bit left that it needs to turn the brake light off.
Now if the emergency brake didn’t fix the situation, it’s time to look into what is causing your Q8’s brake warning light to stay on. The brake light is perhaps the most important warning light of all. We do not recommend driving with this light on at all. Doing so may lead to injury when the brakes fail.
Audi Q8 Brake Warning Light Causes
The brake warning light indicates that your Q8 has detected that one of its major brake components has failed, typically detected through a loss of pressure. You’ll feel a loss of pressure that manifests itself in the form of a “mushy” brake pedal.
If the brake light is only coming on when you push the brakes, that’s a definite indication that the pressure in the brake system is too low. Either the brakes need bled, or there is a leak.
Brake Fluid Leak
Since you’ve already checked the emergency brake handle, now it’s time to check the master cylinder and see if the brake fluid is low or not. Now if it is low, but not empty, adding more may provide a temporary fix.
If the brake fluid looks like it is all the way out, you’ll need to add more, bleed the brakes, and ideally fix the problem so that you aren’t repeating all of this again. If the brake fluid is leaking out over the brake pads and shoes, it means poor brake performance.
Just remember, it had to leak out somewhere, and that adding fluid without fixing the problem is just a temporary solution. The leak can get worse over time and lead to brake failure.
Pressure Differential Switch
Your brake system is divided into two circuits. These circuits cut the brake system in two. That way, if the brake system gets a leak or fails, you still have brakes on half of your Q8’s wheels.
The pressure differential switch measures the difference in pressure between the two circuits and will report that there is a difference by turning on your Q8’s brake warning light. In most vehicles this switch is located in the master cylinder. You’ll see a harness plug in somewhere around there.
Check the Brake Lights
Some vehicles will now activate the brake warning light on the dash if the actual brake lights behind it go bad. Check to see that both of them are lighting up. If not, try replacing the bulb and see if that solves the problem.
How to Turn off Your Q8’s Brake Light
The only way to turn the brake light off is to restore proper line pressure to both brake circuits when the pedal is pushed. If your Q8 is having trouble stopping, or noticeably leaking fluid, don’t drive it. Just have it towed to a mechanic. If you mess up fixing your engine, the vehicle does not move. If you mess up fixing the brakes, it doesn’t stop. That’s infinitely more dangerous.
If your Audi Q8’s brake warning light is on, and you’ve checked the emergency brake, you’ll need to look for a leak in the lines, calipers, wheel cylinders, master cylinder, etc. Good luck diagnosing the issue. If there is anything that you would like to add, please leave a comment below.
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