AutoCodes – Generic – P1B21

P1B21 Code - Hybrid/Electric Vehicle Battery 30 Circuit High 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: P1B21 indicates Hybrid/Electric Vehicle Battery 30 Circuit High 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 900

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 P1B21 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 P1B21 - Hybrid/Electric Vehicle Battery 30 Circuit High Voltage - AutoCodes.com — P1B21 Code - Hybrid/Electric Vehicle Battery 30 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1B21?

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

How to Fix the DTC P1B21?

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 P1B21 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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Need Help with the Code?

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Information for Specific Makes

P1B21 Buick — Hybrid/Electric Vehicle Battery 30 Circuit High Voltage
P1B21 Cadillac — Hybrid/Electric Vehicle Battery 30 Circuit High Voltage
P1B21 Chevrolet — Hybrid/Electric Vehicle Battery 30 Circuit High Voltage
P1B21 GMC — Hybrid/Electric Vehicle Battery 30 Circuit High Voltage
P1B21 Saturn — Hybrid/Electric Vehicle Battery 30 Circuit High Voltage

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 P1B21 Code

1. What are the common symptoms of OBDII code P1B21 (Hybrid/Electric Vehicle Battery 30 Circuit High Voltage)?

The common symptoms of code P1B21 may include a warning light on the dashboard, reduced hybrid system performance, and potential issues with the vehicle's battery functionality.

2. What are the possible causes of OBDII code P1B21?

Possible causes of code P1B21 can include damaged wiring or connectors in the high voltage battery circuit, a faulty battery management system, or issues with the battery itself, such as high voltage leaks.

3. How serious is OBDII code P1B21?

Code P1B21 should be addressed promptly as it relates to the high voltage system in a hybrid or electric vehicle. Continuing to drive with this code present can potentially lead to further damage to the battery system and other components.

4. How can I diagnose OBDII code P1B21?

Diagnosing code P1B21 typically involves using a professional OBDII scanner to read the code and then conducting a thorough inspection of the high voltage battery circuit, including checking for any visible damage or loose connections.

5. Can I drive my vehicle with OBDII code P1B21?

It is not recommended to drive your vehicle with code P1B21 present, as it indicates a problem with the high voltage system in a hybrid or electric vehicle. Continuing to drive may pose safety risks and lead to more severe issues.

6. How can I repair OBDII code P1B21?

Repairing code P1B21 may involve fixing any damaged wiring or connectors in the high voltage battery circuit, replacing faulty components in the battery management system, or addressing issues with the high voltage battery itself.

7. Is it safe to reset the OBDII code P1B21 and continue driving?

Resetting the code without addressing the underlying issue is not recommended, as the problem will likely persist and could lead to further complications with the high voltage system in your vehicle.

8. How much does it cost to repair OBDII code P1B21?

The cost of repairing code P1B21 can vary depending on the specific cause of the issue and the extent of the repairs needed. It is advisable to consult with a professional mechanic for an accurate estimate.

9. Can a DIY enthusiast fix OBDII code P1B21 at home?

While some basic inspections and troubleshooting can be done at home, repairing code P1B21 in a hybrid or electric vehicle often requires specialized knowledge and tools. It is recommended to seek assistance from a qualified technician.

10. How often does OBDII code P1B21 occur in hybrid/electric vehicles?

Code P1B21 related to the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage is relatively rare but can occur due to various factors affecting the high voltage system in these types of vehicles. Regular maintenance and inspections can help prevent such issues.