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Home >> Toyota >> 2025 >> Prius Plug-In Hybrid SE >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Hybrid Battery System (HEV) - Diagnostic Codes (2 Of 2), Symptom Tests & Circuit Tests) >> HYBRID BATTERY SYSTEM (for M20A-FXS) >> DTC P31B5-49: Hybrid/EV Battery Internal Electronic Failure [12/2022 - ] >> Description

DTC P31B5-49: Hybrid/EV Battery Internal Electronic Failure [12/2022 - ]: Description

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The battery ECU assembly monitors its internal operation and will store these DTCs when it detects an internal malfunction.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Warning Indicate DTC Output from Priority Note
P31B5-49 Hybrid/EV Battery Internal Electronic Failure An abnormal signal is detected by the battery ECU assembly (excessive discharging current).
(1 trip detection logic)
Hybrid vehicle control ECU Does not come on Master Warning:
Comes on
HV Battery A SAE Code: P31B5