AutoCodes – Buick – P1B91 Buick

P1B91 Buick Code - Hybrid/Electric Vehicle Battery 58 Circuit Low Voltage

Quick Answer

The Hybrid/Electric Vehicle battery pack contains 288 cells. Common causes include Faulty Hybrid/Electric Vehicle Battery Pack, Faulty Hybrid/Electric Vehicle Battery Interface Control Module. 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: P1B91 Buick indicates Hybrid/Electric Vehicle Battery 58 Circuit Low Voltage.
Common causes: Common causes include Faulty Hybrid/Electric Vehicle Battery Pack, Faulty Hybrid/Electric Vehicle Battery Interface Control Module.
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 701

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 12, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1B91 Buick Description

The Hybrid/Electric Vehicle battery pack contains 288 cells. Groups of three cells are welded together in parallel. There are a total of 96 cell groups in the hybrid/EV battery pack assembly. These cell groups are electrically connected in-series. Each individual cell group is rated at 3.7 V, for a nominal system voltage of 355 V direct current. The battery cells are also grouped together into three sections. The first 90 cells/30 cell groups make up battery section one. This section is adjacent to the cowl and contains batteries 67 through to 96. Battery section two is located behind section one. It is made up of 72 cells/24 cell groups and contains batteries 43 through to 66. The transverse battery section is section number three, it is made up of the remaining 126 cells/42 cell groups and contains batteries 1 through to 42. The three battery sections are individually serviceable components.
The battery energy control module monitors the voltage of the 96 battery cell groups through the four hybrid/EV battery interface control modules. Voltage sense circuits are attached to each individual cell group, and these sense circuits terminate at a connector located on the top surface of the battery section. A serviceable auxiliary battery wiring harness joins this connector to a hybrid/EV battery interface control module, also located on the top surface of the battery section. The hybrid/EV battery interface control module encodes the voltage reading and transmits it to the battery energy control module through the battery control harness. There is one hybrid/EV battery interface control module located on battery sections one and two, and two hybrid/EV battery interface control modules associated with battery section three. The hybrid/EV battery interface control module, battery energy control module wiring harness, auxiliary battery wiring harness, and battery energy control module are all considered serviceable components.
The battery energy control module will determine when a fault condition is present. Diagnostics and system status are communicated from the battery energy control module to hybrid/EV powertrain control module 2 through serial data. The hybrid/EV powertrain control module 2 is the host controller for diagnostic trouble code information.

OBDII Code P1B91 Buick - Hybrid/Electric Vehicle Battery 58 Circuit Low Voltage - AutoCodes.com — P1B91 Buick Code - Hybrid/Electric Vehicle Battery 58 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1B91 Buick?

Faulty Hybrid/Electric Vehicle Battery Pack
Faulty Hybrid/Electric Vehicle Battery Interface Control Module

How to Fix the DTC P1B91 Buick?

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 P1B91 Buick 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 P1B91 Buick Code

1. What does the OBDII code P1B91 mean on a Buick?

The P1B91 code indicates a low voltage issue in the Hybrid/Electric Vehicle Battery 58 circuit, which is part of the high-voltage battery monitoring system.

2. What are common symptoms of the P1B91 code?

Symptoms may include an illuminated check engine light, reduced hybrid system performance, poor fuel efficiency, or the vehicle entering a limp mode.

3. What causes the P1B91 code on a Buick?

Common causes include a damaged or corroded battery wiring harness, a faulty battery sensor, or issues within the hybrid battery pack itself.

4. Can I drive my Buick with the P1B91 code active?

Itâ€™s not recommended, as the vehicle may experience reduced performance or further damage to the hybrid system. Have it diagnosed and repaired as soon as possible.

5. How do mechanics diagnose the P1B91 code?

Mechanics will use a scan tool to confirm the code, inspect the battery circuit wiring and connectors, and test the voltage levels of the hybrid battery system.

6. How is the P1B91 code typically fixed?

Repairs may include replacing damaged wiring, cleaning corroded connectors, replacing a faulty battery sensor, or repairing the hybrid battery pack.

7. Is the P1B91 code covered under warranty for a Buick?

It may be covered under the hybrid or electric vehicle battery warranty, depending on your vehicleâ€™s age and mileage. Check with your dealer for details.

8. How much does it cost to repair the P1B91 code?

Costs vary depending on the root cause, ranging from $100 to fix wiring issues to several thousand dollars if the hybrid battery requires replacement.

9. Can a low 12V battery cause the P1B91 code?

While the 12V battery is unlikely to directly cause this code, voltage issues in the high-voltage hybrid battery system are the primary concern.

10. How can I prevent the P1B91 code from recurring?

Regularly inspect and maintain the hybrid battery system, including checking for corrosion or damage in the wiring and ensuring the battery is operating within specifications.