Peugeot 107 Brake Booster Pressure Sensor Issue

I had something similar on my 107! Those hydraulic brakes can be a pain. Is the error message consistent, or does it come and go? A faulty pressure sensor will definitely give you poor braking. Have you checked the brake lines for any leaks? And when you say 'bled incorrectly', who did the bleeding? Knowing how they did it might help diagnose the issue. Sometimes air gets trapped, causing havoc.

Thanks for the quick reply! The error message is pretty consistent, it's there almost every time I start the car. I haven't seen any visible leaks, but I'll definitely check again more thoroughly. The garage who did the bleeding used some kind of automated system, could that be the problem?

Automated systems should be reliable, but you never know! It definitely sounds like either the sensor itself is shot, or there's a pressure issue related to trapped air as I said before. Given the error message and poor braking, I wouldn't mess around too much myself. Best bet would be to take it to a workshop with proper diagnostic tools to read the brake system-specific error codes. A generic OBD2 reader won't give you enough detail and you might end up chasing ghosts. They can check the sensor readings and brake line pressures properly. Could be a cheap fix (new sensor) or something more involved, but you want to be safe with brakes!

Cheers, that's really helpful advice. I took it to a trusted garage and you were spot on, it was the brake booster pressure sensor. They replaced it, and the braking is back to normal. Total cost was 90€ including the sensor and labor. They also re-bled the system just to be sure. Thanks again for pointing me in the right direction!