AutoCodes – GMC – P1A28 GMC

P1A28 GMC Code - Hybrid Battery 1 Voltage High

Quick Answer

Battery voltage sensors allow the Energy Storage Control Module (ESCM) to monitor the voltage of the batteries in the Energy Storage Box (ESB). Common causes include Faulty Energy Storage Box (ESB) Battery, Faulty Battery Energy Control Module (BECM), Battery Energy Control Module (BECM) harness is open or shorted. 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: P1A28 GMC indicates Hybrid Battery 1 Voltage High.
Common causes: Common causes include Faulty Energy Storage Box (ESB) Battery, Faulty Battery Energy Control Module (BECM), Battery Energy Control Module (BECM) harness is open or shorted.
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 850

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 Feb 15, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1A28 GMC Description

Battery voltage sensors allow the Energy Storage Control Module (ESCM) to monitor the voltage of the batteries in the Energy Storage Box (ESB). The batteries apply voltage to internal input resistors that are connected to the signal circuits of the battery voltage sensors. The module provides ground to the battery voltage sensors through the reference circuit. The ESCM monitors the voltage drop across the battery voltage sensors and uses the inputs for hybrid calculations. When the battery voltage is high, the resistances of the sensors are high and the voltage signals are high. When the battery voltage is low, the resistances of the sensors are low and the voltage signals are low.

OBDII Code P1A28 GMC - Hybrid Battery 1 Voltage High - AutoCodes.com — P1A28 GMC Code - Hybrid Battery 1 Voltage High

What does this mean?

What are the Possible Causes of the DTC P1A28 GMC?

Faulty Energy Storage Box (ESB) Battery
Faulty Battery Energy Control Module (BECM)
Battery Energy Control Module (BECM) harness is open or shorted
Battery Energy Control Module (BECM) circuit poor electrical connection

How to Fix the DTC P1A28 GMC?

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 P1A28 GMC 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 P1A28 GMC code?

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Need Help with the Code?

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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 P1A28 GMC Code

1. What does the OBDII code P1A28 mean on a GMC vehicle?

P1A28 indicates that the hybrid battery pack 1 has a voltage that is higher than the expected range, which may affect the hybrid system's performance.

2. What are the common symptoms of the P1A28 code on a GMC vehicle?

Symptoms may include a check engine light, reduced fuel efficiency, limited hybrid system performance, or the vehicle operating in gasoline-only mode.

3. What causes the P1A28 code to appear?

Common causes include a faulty hybrid battery module, a malfunctioning battery voltage sensor, wiring issues in the hybrid battery circuit, or problems with the battery control module.

4. Can I continue driving with the P1A28 code active?

While you may be able to drive, continued operation could lead to further damage to the hybrid system. It's best to address the issue promptly.

5. How is the P1A28 code diagnosed?

A technician will use a scan tool to read the code, check live data for battery voltages, inspect the battery control module, and visually examine the wiring and connections.

6. What repairs can fix the P1A28 code on a GMC vehicle?

Repairs may include replacing a damaged hybrid battery module, repairing or replacing faulty wiring, recalibrating the battery control module, or replacing the voltage sensor.

7. How much does it cost to repair the P1A28 code?

The cost varies depending on the exact issue, but hybrid battery repairs or replacements can range from $1,000 to $5,000, while wiring or sensor repairs are typically less expensive.

8. Can a low 12V battery cause the P1A28 code?

While not a common cause, a weak or failing 12V battery could affect the hybrid system's performance and trigger related issues.

9. How can I prevent the P1A28 code from occurring again?

Regularly maintain the hybrid battery system, inspect wiring connections, and address any warning lights or issues as soon as they appear.

10. Do I need to take my GMC to a dealership to fix the P1A28 code?

While a dealership has specialized tools for hybrid systems, qualified independent repair shops with hybrid expertise can also diagnose and repair this code.