DTC U0001-87: High Speed CAN Communication Bus - Missing message: Action

WARNING: This page is about a different car, the 2019 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.

Using the Jaguar Land Rover approved diagnostic equipment complete a CAN network integrity test
Refer to the electrical circuit diagrams and check high speed CAN network for short circuit to ground, short circuit to power, open circuit
Using the Jaguar Land Rover approved diagnostic equipment, check front audio control panel, button module for Diagnostic Trouble Code(s) and refer to the relevant DTC index
Using the Jaguar Land Rover approved diagnostic equipment, complete a CAN network integrity test. Refer to the electrical circuit diagrams and check front audio control panel, button module power and ground circuits for open circuit. Check CAN harness between powertrain control module and front audio control panel, button module, repair as necessary