GLC brake booster issue

I understand your concern regarding the brake performance issue. I had a similar issue with my previous Vauxhall Insignia, although the ABS system was affected. Did you notice any unusual noises from the brake pedal before the error message appeared? Have you checked the brake fluid level recently? It could indicate a leak in the brake system. It's possible that the ABS system is not working correctly and affecting the brake performance.

Unusual noises? Hmm, now that you mention it, there was a slight hissing sound before things went south. Brake fluid level seems okay though. If the ABS system is dodgy, would that really cause the brake booster to throw a code? I mean, are they that intertwined?

Yes, the ABS system and the brake booster are often linked. In my case, the faulty ABS module was causing erratic pressure readings, triggering a similar error. Given the hissing sound and the error code, a visit to a workshop for diagnosis is highly recommended. It is important to check the brake system.

Thanks! You were spot on. Took it to a workshop, and turns out the brake booster pressure sensor was toast. They replaced it, re-bled the brake system, and now it's braking like new! Cost me around 90€. Appreciate the help!