AutoCodes – Buick – P1FD9 Buick

P1FD9 Buick Code - Hybrid/EV Battery Interface Control Module 5 Voltage Sensor Circuit Low Voltage

Quick Answer

The hybrid battery contains 192 individual cells. Common causes include Faulty Hybrid/EV Battery Interface Control Module, Hybrid/EV Battery Interface Control Module harness is open or shorted, Hybrid/EV Battery Interface 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: P1FD9 Buick indicates Hybrid/EV Battery Interface Control Module 5 Voltage Sensor Circuit Low Voltage.
Common causes: Common causes include Faulty Hybrid/EV Battery Interface Control Module, Hybrid/EV Battery Interface Control Module harness is open or shorted, Hybrid/EV Battery Interface 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 787

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 27, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1FD9 Buick Description

The hybrid battery contains 192 individual cells. Two cells are welded together in parallel and called a cell group. There are a total of 96 cell groups in the hybrid battery 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 cell groups are joined to form 3 distinct sections. The first 24 battery cell groups make up battery section 1. This section is adjacent to the cowl and contains battery cell groups 73 through 96. The next 28 battery cell groups make up battery section 2. This section is located behind section 1 and contains battery cell groups 45 through 72. The transverse battery section is section number 3 and it contains the remaining 44 battery cell groups 1 through 44. The battery sections also contain two temperature sensors, with one sensor located at each end of the section.
The battery energy control module monitors the voltage of the 96 battery cell groups. The voltage sense lines are attached to each individual cell group, and these sense lines terminate at a connector located on the top surface of the battery section. A voltage sense harness joins this connector to the battery energy control module.
The battery energy control module contains internal interface control modules that monitor specific cell groups.
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 the hybrid powertrain control module 2 through serial data. The hybrid powertrain control module 2 is the host controller for diagnostic trouble code information.

OBDII Code P1FD9 Buick - Hybrid/EV Battery Interface Control Module 5 Voltage Sensor Circuit Low Voltage - AutoCodes.com — P1FD9 Buick Code - Hybrid/EV Battery Interface Control Module 5 Voltage Sensor Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1FD9 Buick?

Faulty Hybrid/EV Battery Interface Control Module
Hybrid/EV Battery Interface Control Module harness is open or shorted
Hybrid/EV Battery Interface Control Module circuit poor electrical connection

How to Fix the DTC P1FD9 Buick?

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 P1FD9 Buick 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 P1FD9 Buick Code

1. What does the OBDII code P1FD9 mean on a Buick?

The P1FD9 code indicates a low voltage issue in the Hybrid/EV Battery Interface Control Module 5 Voltage Sensor Circuit, which monitors the performance of the hybrid or electric vehicle battery system.

2. What are the common symptoms of the P1FD9 code?

Symptoms may include an illuminated check engine light, reduced hybrid or EV performance, poor fuel economy, or limited battery charging and discharging functionality.

3. What causes the P1FD9 code on a Buick?

Common causes include a faulty voltage sensor, damaged wiring or connectors in the sensor circuit, a failing battery interface control module, or an internal battery pack issue.

4. Can I drive my Buick with the P1FD9 code active?

While the vehicle may still operate, driving with this code can lead to reduced performance or efficiency and may cause further damage to the hybrid or EV battery system.

5. How is the P1FD9 code diagnosed?

A technician will typically use a scan tool to confirm the code, inspect wiring and connectors for damage, test the voltage sensor, and check for any additional related codes.

6. How do you fix the P1FD9 code on a Buick?

Repairs may involve replacing the faulty voltage sensor, repairing or replacing damaged wiring, recalibrating the control module, or, in rare cases, addressing internal battery issues.

7. How much does it cost to fix the P1FD9 code?

Repair costs can vary depending on the root cause, but expect to pay between $150 and $500 for sensor or wiring repairs. Battery or module replacements can be significantly more expensive.

8. Can a dead 12V battery cause the P1FD9 code?

A weak or dead 12V battery is unlikely to directly cause this code but may exacerbate electrical issues in the vehicle, potentially contributing to hybrid system faults.

9. Does the P1FD9 code mean my hybrid battery is failing?

Not necessarily. While it can indicate a battery issue, the code is more commonly related to the voltage sensor or its circuit rather than the battery itself.

10. Do I need to reset the P1FD9 code after repairs?

Yes, after completing repairs, the code should be cleared using an OBDII scan tool to ensure it doesnâ€™t reappear and to verify the issue is resolved.