AutoCodes – Cadillac – P0B91 Cadillac

P0B91 Cadillac Code - Hybrid/Electric Vehicle Battery 18 Circuit Performance

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: P0B91 Cadillac indicates Hybrid/Electric Vehicle Battery 18 Circuit Performance.
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 966

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 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0B91 Cadillac 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 P0B91 Cadillac - Hybrid/Electric Vehicle Battery 18 Circuit Performance - AutoCodes.com — P0B91 Cadillac Code - Hybrid/Electric Vehicle Battery 18 Circuit Performance

What does this mean?

What are the Possible Causes of the DTC P0B91 Cadillac?

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

How to Fix the DTC P0B91 Cadillac?

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 P0B91 Cadillac 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 P0B91 Cadillac Code

1. What does OBDII code P0B91 mean on a Cadillac?

P0B91 indicates a performance issue with Hybrid/Electric Vehicle Battery 18 Circuit, suggesting that the voltage or performance of the 18th battery module is outside the acceptable range.

2. What are the common symptoms of code P0B91 in a Cadillac?

Common symptoms include reduced fuel efficiency, a "Check Engine" or hybrid system warning light, decreased battery performance, and potential loss of electric propulsion.

3. What causes the P0B91 code in a Cadillac?

The code can be caused by a faulty battery module, corrosion or damage to wiring/connectors, a malfunctioning battery management system, or issues with the hybrid control module.

4. Can I drive my Cadillac with a P0B91 code?

You may be able to drive the vehicle, but it is not recommended as it could lead to further damage to the hybrid system or reduced performance and efficiency.

5. How is the P0B91 code diagnosed in a Cadillac?

A technician will use a scan tool to read the code, inspect the battery module 18 and its wiring, check for voltage imbalances, and ensure proper functioning of the battery management system.

6. What repairs are needed to fix the P0B91 code?

Repairs may include replacing the faulty battery module, repairing or replacing damaged wiring or connectors, or recalibrating the battery management system.

7. How much does it cost to fix the P0B91 code on a Cadillac?

The cost varies depending on the issue, but replacing a battery module can range from $500 to $2,000, while wiring repairs may cost $100 to $500.

8. Can a weak 12V battery cause the P0B91 code?

No, the P0B91 code is specific to the high-voltage hybrid battery system, not the 12V battery.

9. How can I prevent a P0B91 code from occurring?

Regular maintenance of the hybrid system, keeping connections clean and free of corrosion, and addressing warning lights promptly can help prevent this code.

10. Will clearing the P0B91 code fix the issue permanently?

No, clearing the code without addressing the underlying problem will only reset the warning temporarily, and the issue is likely to return.