This post will be long but very informational and might work for you. So every time I hit the brake my BAS/ESP light will come on on the dash. I checked all my bulbs brand new so I went to the fuse box in the car ( on the left hand side of steering wheel) the brake light fuse there is a BLUE 15 ( first one on the bottom towards the left) looks brand new but I changed it anyway. Car still had the light on when I pressed the brakes. So next I changed the brake light relay( located under the hood in a box on driver side, it’s hidden under the plastic frame on the box but comes out.its usually yellow but if not it’s the relay towards the left.) after pressing the brake and the light comes back next I changed the brake light switch ( located inside the car follow the brake pedal up till you see the switch. There’s a tap to push on then turn the whole switch counter clockwise.) I bought a new one for $12 and before I put it in you must fully extend the plunger if not the switch will not read. Then I put it back in. Make sure all wires are not damaged or if you see any rips fix. There are other connectors under there when you take the plastics off to reach the brake light switch, make sure they are all in properly. I took mines out and put them back in just to be sure. Even the ones where you turn on your lights. There’s wire connectors there too. After assembling the cover back on to everything fitting nice and snugged, i synchronized my ESP. Turn the car o. Left it on neutral ( I have a Manal) turned my steering wheel all the way left then hold for a second then turned my steering wheel right and hold. Then straighten the wheel out. I let the car roll for a second and then slammed on the brakes a few times and held down the brake. Turned the car off waited a few seconds and then turned her back on.when I pressed the brakes, the lights on the dash did not come on. It’s been 3 weeks since then and everything is good except the check engine light ( which is only because I have to buy a Secondary air injection pump ) I write this long story because I was in a jam and really couldn’t spend a lot of money plus I don’t trust other mechanics under my hood lol. So try these steps it might work for you in the beginning or you might have to do everything I did but it will definitely work either way.