P0B31 Possible Causes
- Faulty intelligent battery unit
- Faulty HV battery assembly
What Does It Mean?
How to Fix P0B31 Code
Check the “possible causes” listed above. Visually inspect the wiring harness and associated connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0B31 Possible Symptoms
Check engine light on (or service engine soon warning light)
P0B31 Meaning
The HV battery uses nickel-metal hydride batteries and does not require external charging. The power management control ECU maintains the HV battery SOC (state of charge) at a constant level during driving. The HV battery consists of 28 modules, with each module containing eight 1.2V cells connected in series. The intelligent battery unit monitors the battery block voltage at 14 locations. Each battery block consists of 2 modules in an assembly. The intelligent battery unit, which monitors battery block voltages, determines that a malfunction has occurred if the voltage difference between battery blocks exceeds the standard. When the malfunction detection condition is met, the power management control ECU (HV CPU) illuminates the malfunction indicator light (MIL) and sets a diagnostic trouble code (DTC).