AutoCodes – Toyota – P0B31 Toyota

P0B31 Toyota Code - Hybrid Battery 'D' Voltage Low

Quick Answer

The HV battery uses nickel metal-hydride batteries and does not require external charging. Common causes include Faulty Battery smart unit, Faulty HV battery assembly. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0B31 Toyota indicates Hybrid Battery 'D' Voltage Low.
Common causes: Common causes include Faulty Battery smart unit, Faulty HV battery assembly.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,251

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0B31 Toyota Description

The HV battery uses nickel metal-hydride batteries and does not require external charging. The power management control ECU controls the SOC (state of charge) of the HV battery at a constant level during driving. The HV battery is composed of 28 modules, and each module consists of eight 1.2 V cells in series. The battery smart unit monitors battery block voltage at 14 locations. Each battery block is composed of 2 modules in a set. The battery smart unit, which monitors the voltage of the battery blocks, determines that malfunction has occurred if a voltage difference between the battery blocks exceeds the standard. When the malfunction detection condition is satisfied, the power management control ECU (HV CPU) will illuminates the Malfunction Indicator Lamp (MIL) and set a Diagnostic Trouble Code (DTC).

OBDII Code P0B31 Toyota - Hybrid Battery 'D' Voltage Low - AutoCodes.com — P0B31 Toyota Code - Hybrid Battery 'D' Voltage Low

What does this mean?

What are the Possible Causes of the DTC P0B31 Toyota?

Faulty Battery smart unit
Faulty HV battery assembly

How to Fix the DTC P0B31 Toyota?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0B31 Toyota code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0B31 Toyota Code

What does the OBDII code P0B31 mean on a Toyota?

1. P0B31 indicates that the voltage in Hybrid Battery 'D' is lower than the expected range, often signaling an issue with a specific segment of the hybrid battery pack. 2.

What are the common symptoms of code P0B31 in a Toyota?

Symptoms may include reduced fuel efficiency, diminished hybrid system performance, warning lights on the dashboard, and possible entry into limp mode. 3.

What causes the P0B31 code to appear in a Toyota hybrid?

Common causes include a failing hybrid battery cell or module, corroded or damaged battery connections, or an issue with the battery management system. 4.

Can I drive my Toyota with a P0B31 code?

Driving with this code is not recommended as it may lead to further damage to the hybrid battery system and reduced vehicle performance. 5.

How is code P0B31 diagnosed in a Toyota?

A technician will use a scan tool to read the code, check the hybrid battery voltage levels, inspect the wiring and connections, and test individual battery modules. 6.

How do you fix a P0B31 code on a Toyota?

Repairs may include replacing the faulty battery module, cleaning or repairing corroded connections, or recalibrating the battery management system. 7.

Does a P0B31 code mean the entire hybrid battery needs replacement?

Not necessarily. The issue could be isolated to one or more defective modules within the battery pack rather than the entire battery. 8.

What tools are needed to diagnose and fix a P0B31 code?

Tools include an OBDII scanner, a multimeter to measure voltage, and possibly specialized equipment for testing hybrid battery modules. 9.

How much does it cost to repair a P0B31 code in a Toyota?

Costs vary depending on whether individual modules can be repaired or if the entire hybrid battery needs replacement, ranging from a few hundred to several thousand dollars. 10.

Can I prevent the P0B31 code from occurring?

Regular maintenance of the hybrid battery, keeping connections clean, and avoiding prolonged periods of inactivity can help prevent this code.