RS6 Brake Booster Sensor Failure Affects ABS System

I had a similar brake system issue with my Audi S6 (2005, gasoline). The symptoms matched exactly, weak braking feel and ABS warnings. After diagnostic tools revealed the brake booster pressure sensor fault, further inspection showed the system was improperly bled during previous maintenance. The repair required a complete brake system flush and proper bleeding sequence using specialized equipment. This was definitely a serious vehicle safety concern requiring immediate attention. The incorrect bleeding had introduced air pockets in the hydraulic brakes, causing inconsistent brake performance and false sensor readings. The repair process involved: Full system diagnostic scan, Removal and cleaning of brake fluid reservoir, Professional pressure bleeding of all brake circuits, Brake booster pressure sensor replacement, ABS module recalibration This is not a DIY job, as proper brake system bleeding requires specific diagnostic tools and procedures. While the sensor itself might seem like a simple fix, the entire hydraulic system needs inspection and proper bleeding to ensure safe operation. The symptom combination you describe strongly suggests this could be the same underlying issue. Worth noting that skipping proper diagnosis could mask bigger problems with the brake booster or master cylinder.

Thanks for sharing those details. Your case sounds identical to what happened with my RS6 last year. Had the same brake pedal issues and ABS system warnings. The brake booster pressure sensor replacement plus system bleeding fixed it completely. Before I decide to go ahead with repairs, could you share approximately how much you paid for the full service? Also curious if youve had any other brake-related problems since the repair was done?

Thanks for asking about the follow-up. After the complete brake system service, I havent experienced any additional brake-related issues. The brake performance has remained consistent and reliable. The brake booster pressure sensor repair fully resolved the ABS warnings and weak pedal feel. The total cost for my repair came to 90 Euro, which included bleeding the hydraulic brakes properly and fixing the incorrectly performed previous service. This was actually less expensive than initially quoted, since no replacement parts were needed beyond addressing the sensor issue. The investment was definitely worth it for the peace of mind of having properly functioning brakes. Make sure your mechanic does a thorough system diagnostic before starting the work, as proper brake system bleeding is critical for optimal brake performance. The key is finding a shop that knows the correct bleeding sequence and has the right diagnostic equipment for these brake systems. A properly executed repair should provide lasting results like I experienced.

After getting your valuable input, I decided to take my RS6 to a specialized workshop. The mechanic diagnosed the same brake booster pressure sensor issue you mentioned. The hydraulic brakes needed a complete system flush and proper bleeding. The total repair cost was 850 Euro, including parts and labor. While higher than expected, the brake performance is now perfect, firm pedal feel and no more ABS warnings. The shop used genuine parts and their diagnostic equipment revealed some air pockets in the brake system that were causing the problems. The vehicle safety inspection also confirmed everything is working correctly now. Glad I addressed this properly instead of trying cheaper alternatives that might have compromised the brake system. The whole repair took about 4 hours, but the results were worth the wait and cost.