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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 P1A81-00: Hybrid/EV Battery Stack 1 Delta SOC High (Extreme); DTC P1A86-00: Hybrid/EV Battery Stack 2 Delta SOC High (Extreme) [12/2022 - ] >> Description

DTC P1A81-00: Hybrid/EV Battery Stack 1 Delta SOC High (Extreme); DTC P1A86-00: Hybrid/EV Battery Stack 2 Delta SOC High (Extreme) [12/2022 - ]: Description

WARNING: This page is about a different variant/trim than selected.

The HV battery is composed of 60 cells (3.7 V each) in series. The battery ECU assembly monitors the difference in capacity of each HV battery cell to detect malfunctions of the HV battery.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Warning Indicate DTC Output from Priority Note
P1A81-00 Hybrid/EV Battery Stack 1 Delta SOC High (Extreme) The difference in capacity of each cell of the No. 1 HV supply stack sub-assembly exceeds the specified value excessively.
(1 trip detection logic)
  • HV battery
  • Battery ECU assembly
  • No. 1 traction battery device box
Comes on Master Warning:
Comes on
HV Battery A SAE Code: P1A81
P1A86-00 Hybrid/EV Battery Stack 2 Delta SOC High (Extreme) The difference in capacity of each cell of the No. 2 HV supply stack sub-assembly exceeds the specified value excessively.
(1 trip detection logic)
  • HV battery
  • Battery ECU assembly
  • No. 1 traction battery device box
Comes on Master Warning:
Comes on
HV Battery A SAE Code: P1A86

HINT: 

These DTCs can be stored after clearing the DTCs and driving the vehicle for approximately 10 minutes.