Freestar Brake Booster Error

That sounds eerily familiar. I encountered a similar situation with my 2012 Audi A4. The ABS system went haywire after a brake bleed. Did you, or a mechanic, recently work on your brakes?

Yeah, I had the brake lines flushed and bled a few weeks ago. You think that's the cause? Anything specific I should be looking for?

In my case, the incorrect bleeding introduced air into the ABS module, which caused all sorts of issues. The poor braking effect and the error code are dead giveaways. Based on my experience, I would recommend having a workshop check the brake system. It might be necessary to re-bleed the ABS module using specialized equipment. Hopefully, this fixes your braking problem.

Thanks for the insight. Turns out the brake system wasn't bled properly. Had to replace some parts and get it re-bled at a shop. Cost me 90€, but at least it's fixed.