Audi S1 Brake Booster & Sensor Warning Signs Explained

Had a similar issue with an Audi S3 (2017). The brake system warning and declining brake performance pointed to air in the hydraulic brakes. The brake booster was functioning correctly, but the system needed proper bleeding. The initial symptoms matched exactly, gradually worsening brake performance and warning lights. A pressure sensor triggered the error codes because air pockets created inconsistent pressure readings in the brake lines. The repair involved a complete brake system flush and professional bleeding using specialized equipment. This was definitely a serious vehicle safety concern that needed immediate attention. Air in brake lines can lead to complete brake failure. Key points to check at the shop: Full system diagnostic scan, Brake fluid condition and level, Proper bleeding sequence for all brake circuits, Pressure sensor operation after bleeding, Test drive to confirm proper brake performance This repair requires specific knowledge of bleeding procedures for Audi brake systems. Make sure to use a shop familiar with VAG vehicles. Incorrect bleeding can damage the ABS module or leave air in the system. The root cause often traces back to delayed brake fluid changes or previous incorrect service work. Regular brake fluid maintenance prevents these issues.

Thanks for sharing those details about the brake system repair. The complete brake flush and bleeding procedure you described matches my experience. Those warning lights are definitely not something to ignore. Quick follow-up: What did the repair end up costing you? The pressure sensor readings on my Audi S1 are still inconsistent even after addressing the brake pedal feel issues. Wondering if you had any lingering problems with the hydraulic brakes after the initial fix? My local shop quoted me around 450 Euro for a similar repair, but I want to make sure that sounds reasonable before proceeding. Vehicle safety is obviously the priority here, but would appreciate knowing what others paid for comparable work.

Since my last post, I got the issue fully resolved. The inconsistent pressure sensor readings were caused by incorrectly bled hydraulic brakes, exactly as suspected. The shop did a second bleeding procedure focusing specifically on removing all air pockets from the brake system. The final cost was just 90 Euro for the additional brake system service. This was much more reasonable than the initial quotes. The brake pedal feel is now consistent and firm, and all warning lights have cleared. The pressure sensor now shows correct readings since the air was properly purged from all circuits. 450 Euro sounds quite high for just a brake fluid flush and bleed. Unless they are including additional brake system components in that quote, I would recommend getting a second opinion. Make sure they specifically check the brake booster and pressure sensor operation after bleeding to confirm everything is functioning correctly. The key was finding a shop that knew the proper bleeding sequence for these brake systems. After the proper service, I have had zero issues with brake performance or warning lights.

After getting a second opinion, I ended up going with a different shop that seemed more knowledgeable about Audi brake systems. The total repair came to 280 Euro, which included a complete system flush, professional bleeding, and diagnostic testing. The technician found air pockets in the hydraulic brakes, just as you described. They took extra time to ensure proper bleeding of all circuits. The brake pedal feel is now solid, warning lights are gone, and the pressure sensor readings have stabilized. The brake performance is back to normal, firm pedal and consistent braking force. Really glad I addressed this vehicle safety issue before it got worse. The shop also showed me the old brake fluid which was definitely due for replacement. Appreciate the advice about getting a second quote. Saved quite a bit compared to the initial 450 Euro estimate while still getting quality work done. The brake booster turned out to be fine, it was purely a hydraulic system issue that needed proper bleeding.