AutoCodes – Generic – P1EF8

P1EF8 Code - Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage

Quick Answer

The battery charger compares the high-voltage energy management communication enable hardwire signal with a hybrid powertrain control module 2 serial data message indicating that the high-voltage energy management communication enable signal is active. Common causes include Faulty Battery Charger Control Module, Battery Charger Control Module harness is open or shorted, Battery Charger Control Module circuit poor electrical connection. 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: P1EF8 indicates Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage.
Common causes: Common causes include Faulty Battery Charger Control Module, Battery Charger Control Module harness is open or shorted, Battery Charger Control Module circuit poor electrical connection.
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 1,174

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 Apr 25, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1EF8 Description

OBDII Code P1EF8 - Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage - AutoCodes.com — P1EF8 Code - Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1EF8?

Faulty Battery Charger Control Module
Battery Charger Control Module harness is open or shorted
Battery Charger Control Module circuit poor electrical connection

How to Fix the DTC P1EF8?

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 P1EF8 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.

Need more information about the P1EF8 code?

Need more information on how to fix the P1EF8 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1EF8 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1EF8 Buick — Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage
P1EF8 Cadillac — Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage
P1EF8 Chevrolet — Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage
P1EF8 GMC — Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low Voltage
P1EF8 Saturn — Battery Charger Control Module High-Voltage Energy Communication Bus Enable Circuit Low 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 P1EF8 Code

1. What does the OBDII code P1EF8 mean?

P1EF8 indicates an issue with the Battery Charger Control Module detecting a low voltage in the high-voltage energy communication bus enable circuit, often related to hybrid or electric vehicles.

2. What are the common symptoms of P1EF8?

Common symptoms include the check engine light turning on, reduced hybrid or EV performance, charging system malfunctions, and potential loss of regenerative braking.

3. What causes the P1EF8 code to appear?

Possible causes include faulty wiring or connectors in the high-voltage communication bus, a malfunctioning battery charger control module, or a blown fuse in the circuit.

4. Can I drive my vehicle with the P1EF8 code active?

Driving with this code may be possible but is not recommended, as it could lead to further damage to the charging system or high-voltage components.

5. How is the P1EF8 code diagnosed?

A mechanic will use a scan tool to confirm the code, inspect the wiring and connectors in the high-voltage energy communication bus, and test the battery charger control module for proper operation.

6. What repairs can fix the P1EF8 code?

Repairs may include replacing damaged wiring or connectors, replacing the battery charger control module, or replacing a blown fuse in the circuit.

7. How much does it cost to repair the P1EF8 code?

Repair costs can vary but typically range from $150 to $1,000, depending on whether minor wiring repairs or a battery charger control module replacement is required.

8. Can a low 12-volt battery cause the P1EF8 code?

While unlikely, a weak or failing 12-volt battery can sometimes contribute to communication issues in hybrid or EV systems and should be tested as part of the diagnosis.

9. Will clearing the P1EF8 code fix the problem?

Clearing the code without addressing the underlying issue will not fix the problem, and the code is likely to return.

10. Is the P1EF8 code specific to any vehicle brand or model?

This code is most commonly found in hybrid or electric vehicles from manufacturers like GM or Toyota but can apply to other brands using similar high-voltage systems.