Citan Electric low tire pressure ABS and steering issues

I had a similar issue with my Opel Insignia, though it was a diesel. The TPMS flagged a pressure issue, but the tire gauge was normal. I suspected a faulty sensor in the tire monitoring system. Have you considered that? Also, does the vibration change with speed, or is it constant?

The vibration increases with speed. Could a single faulty sensor trigger the ABS lamp and affect power steering?

A faulty sensor can cause odd readings and trigger unrelated warnings. I cannot say if it would affect the ABS or power steering directly, but modern vehicles are complex. The ECU might be misinterpreting the sensor data. A defective valve could be the problem, but I recommend a thorough inspection. I took mine to the shop.

The workshop confirmed a defective valve in one of the tires, causing pressure loss and triggering the warnings. The repair, including valve replacement and recalibration of the tire pressure monitoring system, cost 280€.