GLA Hybrid brake booster pressure sensor problem

I had similar issues with my GLA. The error message, poor braking, the whole nine yards. The ABS system relies heavily on the hydraulic brakes, and if the system wasn't bled correctly after some work, air can definitely wreak havoc. Did you recently have any work done on the braking system? Specifically, were any replacement parts installed that might have necessitated bleeding the lines? Also, what diagnostic tools did you use to pull the error code? Knowing the specific code might help narrow down the problem.

Thanks for the quick reply! Good to know I'm not alone in this misery. No recent work on the brakes, though. That's what's baffling me. As for diagnostic tools, just a generic OBD2 reader, nothing fancy. You think a proper scan with more specialized diagnostic tools might reveal more?

It's always possible a deeper scan reveals more. If you haven't touched the brakes recently, a bad sensor is definitely a possibility, but air in the system can manifest even without recent work, especially if there was a pre-existing minor leak somewhere. Given the symptoms – the error message AND the diminished brake performance – I'd advise getting it to a workshop ASAP. They can properly diagnose the sensor, check the brake lines, and ensure the ABS system is functioning correctly. Don't risk your safety guessing.

Appreciate the insight! Looks like a trip to the workshop is in order. Turns out the brake booster pressure sensor was indeed toast. 90€ for the replacement parts and labor, and she's braking like new again. Thanks for confirming my suspicions!