Terraza Brake Booster Failure Causing Soft Pedal Issues

Had a similar issue on my 2008 Buick Enclave. The soft brake pedal and reduced braking performance turned out to be more than just a pressure sensor problem. The hydraulic brakes needed a complete system bleed due to air in the lines, plus the brake booster was failing. After inspection, they found moisture had entered the brake system through deteriorated seals, which caused internal corrosion. The brake pedal feel got progressively worse over a few weeks. The replacement parts included a new brake booster, master cylinder seals, and several brake line sections that had corroded. This was definitely a serious safety issue requiring immediate attention. The complete repair involved: Full brake system bleed to remove air, Brake booster replacement, Master cylinder rebuild, Brake line replacement in corroded sections, Pressure sensor calibration The job took about 2 days to complete properly. Would strongly recommend having it checked soon, as compromised braking can be dangerous. The symptoms match what I experienced before the repairs. The mechanic explained that on these models, once moisture enters the system, it tends to cause cascading failures in multiple brake components. Regular brake fluid changes could have prevented some of the damage.

Thanks for sharing your experience with the brake system repair. Mine is fixed now and the brake pedal feels firm again. The symptoms were almost identical to what you described with the soft pedal and reduced brake performance. Just wondering how much you ended up paying for all those replacement parts and labor? Also, has everything been working properly since the repair, or have you noticed any other brake-related issues popping up? I want to compare costs since these hydraulic brake repairs can vary quite a bit between shops. Plus it would help others in the forum who might face similar problems with their vehicles.

Just got back to update on the costs. The brake booster pressure sensor failure was fixed and the system is working perfectly now. Since having the brake system bled correctly and properly calibrated, the brake pedal response has been firm and consistent. Total cost came to 90 for the repair, which was much less than expected given all the initial concerns. My brake performance has remained solid for several months now with no warning lights or soft pedal issues returning. The mechanic mentioned that catching these problems early helped avoid more extensive damage to other components in the system. For anyone else facing similar symptoms, having the brake system inspected promptly can prevent the cascading failures that often happen when moisture infiltrates the system. Regular maintenance and brake fluid changes are also key to preventing these issues from developing. The investment in proper repairs was definitely worth it for the safety and reliability improvements. Much better than risking a more expensive fix down the road.

Thanks for all the input everyone. Following up on my initial post about my Terraza, I finally got the repairs done last week. The mechanic hooked up their diagnostic tools and traced the issue to both the ABS system and brake booster. The repair ended up being simpler than expected. They flushed the hydraulic brakes, replaced the faulty pressure sensor, and recalibrated the system. Total cost was about €400 including parts and labor. The brake pedal is nice and firm now, with no more warning lights on the dash. Really glad I got it fixed when I did, the mechanic showed me how the old sensor was starting to corrode which could have led to bigger problems. The braking performance is back to normal and the car stops great now. Definitely learned my lesson about not waiting too long when brake issues first appear.