Rifter Electronic Parking Brake Fault

The symptoms you describe strongly suggest an issue within the electronic parking brake system itself. Does the error code specify which side is affected, or is it a general system fault? Considering the mileage, it's quite possible the electric motor within one of the brake calipers is starting to fail, a common issue I've seen in electronically controlled brake systems. Did you check the brake fluid level?

The error code doesn't specify a particular side, and the brake fluid level is optimal. Given your experience, does this lean even more towards the electric motor in the brake caliper?

Given the additional information, my suspicion indeed falls on the electric motor within the brake caliper. While a faulty brake sensor could cause similar symptoms, a general system fault without side-specific errors points more towards a motor issue. At this point, a workshop visit for proper diagnostics is advisable. They'll be able to confirm the fault and perform the necessary repairs.

Appreciate the advice. It's pretty much as you called it; workshop confirmed the electric motor in the brake caliper was defective, and I authorized the replacement. Final bill came to 505€. Thanks for pointing me in the right direction!