Prius Triangle of Death: What every warning light means
When a Prius lights up the master warning triangle plus check engine, brake, and battery icons all at once, that's the so-called 'triangle of death.' Here's what's actually going on.
What it means
The master warning triangle is Toyota's catch-all 'something is wrong with a critical system.' When it shows up alongside check engine, the red brake light, and the battery icon, the hybrid system has detected a fault serious enough that it wants you to stop driving and get it diagnosed.
Vehicles where we see this most
- Toyota Prius (2nd gen, 2004–2009, most common)
- Toyota Prius (3rd gen, 2010–2015)
- Toyota Camry Hybrid
- Lexus CT200h
Most-likely causes
- Hybrid battery pack failure (most common cause on a 10+ year old Prius).
- Failing 12V auxiliary battery. The cheap fix that gets misdiagnosed as a hybrid battery problem all the time.
- Inverter coolant pump failure (separate, expensive, but not the hybrid pack).
- Throttle body or MAF sensor. Rare combinations, but they can light up the same cluster.
Is it really the battery?
Often, but not always. On a high-mileage 2nd-gen Prius, the triangle of death is the hybrid battery something like 70–80% of the time. But a dying $200 12V battery causes the same warning cluster, which is why we always ask people to check that first before booking us.
What to do next
- Don't keep driving. Pull over safely. The car has decided not to drive normally for a reason.
- Test or replace the 12V auxiliary battery first. If yours is more than 4 years old, replace it before doing anything else. AGM only.
- If the lights stay after a fresh 12V, get codes scanned. P0A80 + P3011-P3030 = hybrid pack. Anything else, call us before assuming.
Not sure if this is what's wrong with your car?
Five questions, built by our techs. We'll tell you honestly whether it sounds like the pack, or something cheaper.