Internal Backup battery (BuB) is empty or damage
â–¶ How to fix
Replace the battery and check if DTC still remains. If the DTC still remains active after replacing battery the failure is located in the RTC ECU, change unit.
What you'll see
No driver-visible symptom recorded.
System reaction
If the battery is below 2.2 V for more than 1 hour the battery is damaged. Therfore it is not possible to charge the battery.
Diagnostic depth
Detection
The battery voltage is below 2.2 volt.
Possible cause
Malfunctioning battery due to age or after long storage without charging. Missuse of battery switch.