Does your RRE have the LID ( Load Information Display ) hanging from the roof?

Have a look at the BT RRE 140 need service manual thread in the technical area of the forum as somebody else has the exact same problem with an RRE 140:

Error code 1 : 516 = MCU or CID has not received a response within 70 ms via CAN1

Check:

1.Check that CAN 1 is intact in terms of wiring harness, final resistance and contacts.

2.Disonnect the battery. Check that the resistance between [X41:3] and [X41:4] is between 54 & 66 ohm.

3.Deactivate and disconnect LID, DHU and collision sensor. Activate and then connect them one by one to find out which unit gives rise to the communication error.

You need BT Truck Com diagnostic software to carry out number 3.