VW Phaeton Brake Pedal Softness + Booster Sensor Issues

Had nearly identical symptoms on my 2005 VW Passat 2.0T. The soft brake pedal combined with error codes pointed to incorrectly bled brake system rather than a faulty brake booster sensor. The previous repair shop had not properly bled the system during routine brake maintenance, allowing air to remain in the lines. This created vehicle safety concerns since air pockets reduce hydraulic pressure and compromise braking performance. The fix required complete system bleeding using professional diagnostic tools to ensure proper sequence and pressure. The mechanic also performed a full brake system inspection revealing no other component failures. The brake booster and sensor tested within normal parameters. Important to note this was a serious safety issue requiring immediate attention, as compromised braking could lead to accidents. After proper bleeding, the brake pedal returned to normal firmness and all error codes cleared. Based on your description, recommend having a certified shop perform a complete brake system diagnostic before replacing any components. Air in the lines often mimics sensor failures and improper bleeding is a common issue after brake work.

Thanks for sharing your experience. Really glad to hear it was just trapped air causing the soft brake pedal rather than a failed pressure sensor. Getting my VW checked next week to rule out any ABS system faults first. Could you share roughly what the brake system diagnostic and bleeding service cost at your shop? Also wondering if youve had any recurring brake performance issues since the repair was done?

After getting my car checked as suggested, it turned out you were absolutely right. The brake booster pressure sensor was working correctly, the issue stemmed from incorrectly bled brake lines after previous maintenance. The complete brake system diagnostic and bleeding service cost 90€, which was reasonable considering the improvement in brake performance. The mechanic thoroughly flushed the hydraulic brakes and ensured no air remained in the system. Since having this fixed, my braking system has performed flawlessly with no recurring issues. The brake pedal maintains proper firmness and all warning lights have stayed off. Vehicle safety is back to factory specifications, and the car stops predictably every time. Just wanted to follow up since your advice helped identify the real problem. Getting proper brake system maintenance from a qualified shop made all the difference, rather than unnecessarily replacing sensors.

Thanks so much for sharing that experience. After following your advice, I took my VW to a certified shop yesterday. The mechanic found air trapped in the brake lines, just like you mentioned. The brake booster and pressure sensor tested fine. The complete brake system diagnostic with professional bleeding cost 120€. The hydraulic brakes now feel firm and responsive again. All dashboard warnings cleared up right after the service. Really glad I asked here before replacing parts unnecessarily. The proper brake system maintenance was exactly what my car needed. Safe driving feels great with properly functioning brakes.