Seat Mii exhaust noise issue

Louder exhaust noise and error codes related to the exhaust flaps often point to a failure in the exhaust components, specifically either the flap actuator or the exhaust valves themselves. Since you mentioned noisy engine operation after a cold start, it is possible the exhaust valves are not opening and closing as they should. Have you checked the flap actuator for any physical damage or corrosion? If the error memory contains codes specifically referencing the flap actuator, that component is the most likely culprit. Consider it akin to a circuit breaker tripping; the root cause needs addressing.

Thanks for the quick reply. I've visually inspected the flap actuator, but couldn't spot any obvious damage. The error code does point directly to it. Is there a way to test the actuator definitively before replacing it, or is it more of a process of elimination?

Given that the error code specifically references the flap actuator and you're experiencing increased exhaust noise along with those cold start issues, it's highly probable the actuator is indeed faulty. Further diagnostics might involve testing the signal being sent to the actuator, but without specialized equipment, it's difficult to confirm definitively. Considering the likely cause and symptoms, replacement is a reasonable next step. If you're not comfortable with replacing exhaust valves or the actuator yourself, the repair cost of 190€ seems fair for replacing the actuator at a workshop.

Bit the bullet and got it sorted. Cost me 190€ at the local garage. Turns out the flap actuator was indeed toast. Thanks for confirming my suspicions and pointing me in the right direction. Running much quieter now, especially on cold starts.