Q5 Brake Booster Sensor Failure Causes Safety Risk

Having some experience with brake system issues, I dealt with almost identical symptoms on my 2017 Q3 diesel. The hydraulic brakes started showing similar warning messages and reduced brake performance. After noticing changes in brake pedal feel, I took it to a workshop. The main issue turned out to be incorrectly bled brake lines, which affected the entire brake system functionality. The repair was relatively straightforward, they performed a complete professional brake system bleeding procedure which resolved both the warning light and restored normal brake pedal response. Total cost was 90 Euro for the service, and it took about an hour. The most important thing was getting it fixed quickly, as compromised brake performance is a serious vehicle safety concern. To provide more specific advice about your situation, could you share: Current mileage on your Q5? When was your last brake service completed? Are you experiencing any unusual sounds when pressing the brake pedal? Did the warning light appear suddenly or gradually over time? These details would help determine if your issue is similar to what I experienced or if it might be something different.

Thanks for sharing the experience. My Q5 has 149243 KM, and I had the last major service including brake fluid change about 14000 KM ago. After reading about the ABS system and brake booster issues online, I was worried about a major repair. Glad to hear it might be something simpler like air in the brake lines. No unusual sounds from the brake pedal, but the warning appeared quite suddenly during a longer drive. Will have it checked at a workshop this week since the replacement parts seem reasonably priced if needed. Safety comes first with brake-related issues.

Good to hear back about your Q5. The sudden warning during a longer drive, combined with the changed pedal feel but no unusual sounds, does sound very similar to what I experienced. While my initial brake line bleeding fixed the issue temporarily, I should mention that it came back after about 6000 KM. The root cause in my case turned out to be a faulty brake booster pressure sensor, which was causing incorrect readings and affecting brake performance. The replacement parts cost was 180 Euro plus labor. The workshop used professional diagnostic tools to confirm this before replacing the sensor. Since your last brake fluid service was relatively recent at 14000 KM, its unlikely to be just a routine maintenance issue. Based on your mileage of 149243 KM, the pressure sensor might be showing normal wear and tear. When they check yours, have them specifically test the sensor functionality. The good news is that even if you need the sensor replaced, its a straightforward repair that significantly improves brake performance and restores proper system function. Make sure to get a detailed diagnostic report from the workshop to keep with your service records.

The brake-related problems you mentioned with my Q5 turned out to be exactly what you described. The workshop confirmed it was indeed a faulty brake booster pressure sensor after running their diagnostics. Total repair came to 220 Euro including parts and labor, slightly more than your case but still reasonable for a critical brake system component. They also performed a complete system bleeding as a precautionary measure. The brake performance is now back to normal, warning light is gone, and pedal feel is perfect. You were spot on about the wear and tear factor at my mileage level. Really appreciate your detailed insights about the ABS system and potential issues. Having this information beforehand helped me better understand what the workshop was explaining. Thanks for sharing your experience, it definitely helped ease my concerns about potentially major replacement parts being needed. The repair team also gave me a full diagnostic report for my records, which is great for documenting the brake system maintenance history.