Sienna Hybrid Overvoltage Issue

I had a similar issue with my older Sienna. Could you specify which systems are reporting faults? Knowing the affected modules might help narrow down the cause. Have you checked the voltage regulator? A faulty regulator can cause overvoltage issues. Also, do you know the exact error codes?

Error codes relate to the power management ECU and the hybrid control module, both indicating high voltage. Sporadic errors from the ABS and stability control systems too. I haven't tested the voltage regulator yet, prioritizing the battery. Could a faulty voltage regulator cause such widespread issues, even with a relatively new battery?

Yes, a faulty voltage regulator can absolutely cause widespread problems, even with a newer battery. It can allow excessive voltage to flow, potentially damaging components. Given the error codes, investigate the voltage regulator. However, with so many issues, it might be best to take it to a workshop, as diagnosing overvoltage issues requires specialized tools.

I took the Sienna to a trusted workshop. The high-voltage battery had an internal fault, leading to the overvoltage. The repair, including a new battery and diagnostic work, came to 290€. Checking the voltage regulator was spot on, although in this case, it was a symptom rather than the root cause.