Circuit Description - DTC P3106 - Information Codes 209, 210, 211: Notes

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

When using an OBD II scan tool other than TOYOTA hand-held tester, check all the steps.
When using TOYOTA hand-held tester, confirm the information code and check it.

The HV ECU monitors the communication signal from the ECM and if it cannot monitor it due to noise or other reasons, judges as an error.