Prius Won't Start or Enter Ready Mode: Complete Troubleshooting Guide
If your Prius won't enter Ready mode, the hybrid battery is a likely culprit. Here's how to diagnose and fix the problem.
What Does "Ready Mode" Mean?
When you press the power button in a Prius, the system goes through checks and then displays "READY" on the dash, indicating the hybrid system is operational. If the system can't enter Ready mode, the car won't drive. This is often related to the hybrid battery.
Common Causes When Prius Won't Enter Ready Mode
- Failed hybrid battery — The most common cause, especially in Arizona heat
- 12V auxiliary battery failure — The 12V battery powers the computer; if it's dead, the car won't start
- Inverter water pump failure — Prevents the cooling system from operating
- Hybrid system relay failure — Contactor issues in the battery system
- Blown fuse or wiring issue — Electrical faults in the hybrid system
DTC Codes to Look For
- P0A80 — Replace Hybrid Battery Pack
- P0A7F — Hybrid Battery Pack Deterioration
- P3011–P3024 — Battery block faults
- P0A01 — Hybrid Battery System Isolation Fault
- P0A93 — Inverter Converter System malfunction
Arizona Heat: A Leading Cause
In Phoenix, the most common reason a Prius won't enter Ready mode is a failed hybrid battery. Arizona's extreme temperatures shorten battery life significantly, and many Prius owners in the Phoenix area need replacement earlier than the national average.
What to Do If Your Prius Won't Start
First, check if the 12V battery is charged. If the 12V is fine and you're still not entering Ready mode, the hybrid battery is the likely culprit. We offer mobile diagnostic and replacement services:
- Prius Gen 2 (2004–2009): 28-cell battery starting at $800
- Prius Gen 3 (2010–2015): 34-cell battery starting at $1,000
We also service Camry Hybrid, Avalon Hybrid, and Lexus hybrids. Call (602) 845-9291 or book online.