For all vehicle owners, regular maintenance should come as second nature especially as most new cars remind us when an oil change is due or tire pressure level is low. However, in a Toyota Prius, the “red triangle of death” is similar to a check engine light on standard combustion vehicles.
The warning light could be something as simple as a low oil pressure warning, or it could mean something more. In the event your hybrid vehicle is experiencing a more serious issue, having the codes scanned and diagnosed is your first call to action.
In this article, The Hybrid Geek delves into common causes for the warning and how to quickly get you back on the road by fixing the red triangle of death in hybrid vehicles.

Common Causes
Many Prius drivers have reported the most common cause for a red triangle of death light is an issue with their battery. Typically, the codes that come up after a diagnostic are P0A80 and P3000.
The P300 code refers to the Prius’ battery control system. When this code appears, the problem is typically caused by several sources, but it means there is an issue with the HV battery’s ECU. Signs that your Prius is experiencing this common problem are:
- Fuel gauge fluctuations and incorrect readings.
- Blower fan regularly kicks on meaning the hybrid is getting heated up, thus, battery capacity depreciates.
- Drastically reduced gas mileage with no other cause.
- Dash lights displaying, such as red triangle of death.

The P0A80 code is a sign that your hybrid battery pack is experiencing cell failure, which is shown as a malfunction in the vehicle’s battery management system. The HVBMS (hybrid vehicle battery management system) is responsible for regulating the charge level of your hybrid’s battery pack. By monitoring battery temperature, voltage, and individual cell resistance, the HVBMS diagnose your battery pack’s condition and optimum charging level.
When the HVBMS reports inconsistent battery or cell temperature, a red triangle of death will be displayed and a P0A80 code is present. Although the hybrid battery pack has 204 cells, it only takes 1 failing or bad cell to cause the code and it means the battery is on borrowed time.
How to Fix P3000
As we’ve discussed in past articles, a failing battery pack doesn’t necessarily mean you need a new one. Starting with a diagnostic service, a licensed HV mechanic can help offer options. One of the common options is obviously a new battery pack in the event there are more than just 1 bad cells within the pack.
Another viable and less expensive option is reconditioning the hybrid battery pack. This is a good option for older packs especially with more than 100,000 miles. The state of health check will help give you a starting point and your hybrid mechanic shop can offer you the best option for your situation.
Lastly, preventative care is also your best bet to keep the battery pack functioning properly as long as possible. Services such as cell testing and state of health checks can help give you an idea of possible problems which may occur in your hybrid.
How to Fix P0A80
Again, starting with a diagnostic service will help you understand why the red triangle of death has offered up code P0A80. Typically, the best fix for this is to repair damaged cells (or replace dead ones) if possible. Reconditioning the battery can also rectify the issue, but your hybrid mechanic will be the best person to make the final decision.
Final Thoughts
If you are experiencing this warning sign on your Toyota Prius or hybrid vehicle, it’s time to get a state of health check. The Hybrid Geek offers comprehensive care, from free state of health checks, to full battery rebuild/recondition.