Brake Pedal Hard and Engine Won’t Start

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Jul 17, 2019 | 12:20 AM

KCV

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Joined: Feb 2018

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From: Texas

Brake Pedal Hard and Engine Won’t Start

Intermittently on my 2018 A8 Stingray when I attempt to push the brake pedal and push the Start button to start the engine nothing happens. The brake pedal feels rock hard stuck and won’t push in at all. I get a dash message that says something like, Push Brake To Start Engine. After several attempts the brake pedal will eventually push in normally and the engine can be started with the Start button. This has happened several times. Any ideas what is wrong?

Last edited by KCV; Jul 17, 2019 at 12:22 AM.

Jul 17, 2019 | 01:00 AM

The HACK

Burning Brakes

Joined: Apr 2018

Posts: 1,051

Likes: 690

Brake vacuum boost leak.

Jul 17, 2019 | 08:23 AM

Mr. Jones

Drifting

Joined: Oct 2002

Posts: 1,335

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From: Bedford Va.

I have a hard brake pedal on startup after the car has sat for days.
Never had a start issue, just push harder.
If this is abnormal and a booster leak I would like to hear from others.

Jun 16, 2021 | 07:05 PM

jbenderl

Advanced

Joined: Aug 2018

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I just had the vacuum pump replaced to address the hard pedal problem (happens overnight). Sadly, it did not solve the problem.

Jun 17, 2021 | 10:23 AM

ersatz928

Melting Slicks

Joined: Mar 2001

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From: New Jersey

The brake booster unit has a vacuum leak.

Jun 19, 2021 | 08:10 PM

Avanti

Race Director

Joined: Mar 2001

Posts: 19,973

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From: Bonneville Salt Flats

My brake pedals on all my vacuum-assisted cars is hard before start. I've no idea, though, why your car is failing to start, but it's not the fault of the brakes. I'd start by cleaning the battery terminals/cable-ends and checking the battery (especially if more than 3-years old). Battery longevity is a total crap-shoot. All the best.

Jun 20, 2021 | 08:24 AM

Tinkertech

Melting Slicks

Joined: Feb 2018

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From: North Texas

Check the brake switch is properly aligned and functioning correctly.

Jun 20, 2021 | 04:23 PM

Sailez51

Heel & Toe

Joined: Dec 2017

Posts: 18

Likes: 4

From: Los Angeles

Definitely check brake switch . My M7 did the same and message to press clutch appeared . Dealer replaced clutch switch on warranty and problem was solved . Yours is obviously auto and break switch needs to be looked at .