ABS and ESP lights on all the time. I bought Audi A4 B6 2004 only two months ago. It started in heavy rain.

The ESP system means the Electronic Stability Program. If the ESP & ABS lights on the dashboard permanently the ESP & ABS system is faulty. You must access the ESP & ABS Electronic Control Unit (ECU) memory for pull out all DTC (Diagnostic Trouble Codes), using diagnostic equipment connected to the data link connector of the car (placed in dashboard, under a plastic cover above the ashtray). Then you will be full informed about bad pieces (e.g.: front right wheel abs sensor interrupted, ...). After bad pieces replacement you will be able to erase all faults memored by ESP & ABS ECU, in other words reset the ESP & ABS system and turn off the warning lamp on dashboard.