Modus heavy steering and vibration

Heavier steering and vibrations? Has the wheel alignment been checked recently? Also, does the traction control light come on?

Wheel alignment seems okay. But the traction control light... that's interesting. Would a faulty steering angle sensor cause that?

It can, yes. If the sensor's faulty, it can send incorrect signals to the car's computer, which then affects the traction control and power steering. Best to get it checked at a workshop. Sounds like a sensor replacement might be needed.

Turns out it was a faulty steering angle sensor needing recoding. Replacement and recalibration fixed it, cost 195€. Thanks for pointing me in the right direction.