207- ABS fault

[tinop1]

Peugeot 207 -06 1.4 KFU (ET3J4)
The brake pedal is soft and the onboard computer reports the following faults: ABS system faulty, Anti‑theft system faulty, and Antipollution fault.
The ABS unit was replaced with another one from a scrapyard, but the fault did not go away. The error code is still U0121.
Does anyone have experience on where to start looking for the fault next.

- U0121
Data bus, anti-lock brake system (ABS) control module - no communication
- P1614
SBDS Interactive Codes
- P0500
Vehicle speed sensor (VSS) - circuit malfunction
- U0415
Invalid data received - anti-lock brake system (ABS) control module

[RichardW]

No Comms with the ABS unit - it might be offline? Although it appears to be talking, but I'd want to see it on a different scan tool. Really needs a check of power and earth at the ABS unit next..