AutoCodes – Generic – P1A28

P1A28 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 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 1,649

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

What does this mean?

What are the Possible Causes of the DTC P1A28?

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?

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 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 code?

Need more information on how to fix the P1A28 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1A28 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1A28 Buick — Hybrid Battery 1 Voltage High
P1A28 Cadillac — Hybrid Battery 1 Voltage High
P1A28 Chevrolet — Hybrid Battery 1 Voltage High
P1A28 GMC — Hybrid Battery 1 Voltage High
P1A28 Saturn — Hybrid Battery 1 Voltage High

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 Code

1. What does the OBDII code P1A28 mean?

P1A28 indicates that the hybrid battery voltage on Bank 1 is higher than the manufacturer-specified range, typically due to a fault in the battery or its monitoring system.

2. What are the common symptoms of code P1A28?

Symptoms may include an illuminated check engine light, reduced fuel efficiency, limited vehicle performance, or warnings related to the hybrid system.

3. What causes the P1A28 code to appear?

Common causes include a malfunctioning hybrid battery module, a faulty battery voltage sensor, a wiring issue, or a problem with the battery control module.

4. Can I continue driving with a P1A28 code?

While the vehicle may still operate, driving with this code can strain the hybrid system and potentially lead to further damage. Itâ€™s best to address the issue promptly.

5. How is the P1A28 code diagnosed?

A technician will use a scan tool to check freeze frame data, inspect the hybrid battery voltage readings, and test the battery control module and related wiring for faults.

6. What repairs can fix the P1A28 code?

Repairs may include replacing a failed hybrid battery module, repairing or replacing damaged wiring, or reprogramming or replacing the battery control module.

7. How much does it cost to fix a P1A28 code?

Costs can vary widely depending on the issue, ranging from $100 for minor wiring repairs to several thousand dollars for hybrid battery replacement.

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

A low or failing 12V battery can sometimes contribute to hybrid system errors, but itâ€™s unlikely to be the sole cause of P1A28. A proper diagnosis is necessary.

9. Can resetting the code fix the P1A28 issue?

Resetting the code without addressing the underlying cause will likely result in the code returning. Repairs are needed to resolve the issue.

10. Is the P1A28 code specific to certain vehicles?

Yes, P1A28 is specific to hybrid vehicles and may be more common in certain makes and models that use similar hybrid battery systems. Always consult the service manual for your vehicle.