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Toyota Prius Gen2 12V Auxiliary Battery Failure — Toyota Prius 2004 | MyCarFault
⚪ UNSOLVED No confirmed fix yet · Be the first to help

Toyota Prius Gen2 12V Auxiliary Battery Failure

Toyota Prius 2004 1NZ-FXE 1.5 Hybrid
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⚡ Quick Summary
Severity Level
High
Safe to Drive?
✅ Safe to Drive
Safety Impact
No direct safety impact reported by owners
Urgency Level
🟠 Fix Soon

The 12V auxiliary battery in Gen2 Prius fails after 4-6 years, causing the car to appear completely dead, display multiple warning lights or fail to enter Ready mode. This is the most common Prius breakdown. The 12V is a standard AGM battery (size S34B20R) and costs £80-150 to replace. Preventive replacement every 5 years is recommended.

Repair / Solution

No confirmed fixes yet. Share yours below.

⚠️ Wrong Diagnosis?

No commonly reported misdiagnoses for this fault yet. If you have replaced a part that did not fix this Toyota Prius 2004 problem, submit a wrong diagnosis report — it helps other drivers avoid the same costly mistake.

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