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Engine-Codes – Generic – P15FF

P15FF Code - Battery Monitor Sensor Signal Message Counter Incorrect

Quick Answer

The P15FF code indicates a problem with the Battery Monitor Sensor, specifically related to the signal message counter being incorrect. Common causes include Faulty Battery Monitor Module, Battery Monitor Module harness is open or shorted, Battery Monitor Module circuit has a 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
P15FF indicates Battery Monitor Sensor Signal Message Counter Incorrect.
Common causes
Common causes include Faulty Battery Monitor Module, Battery Monitor Module harness is open or shorted, Battery Monitor Module circuit has a 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.
What is this?
Table of contents Created and updated by William Orellana on Oct 03, 2025
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Code P15FF Description

The P15FF code indicates a problem with the Battery Monitor Sensor, specifically related to the signal message counter being incorrect. The Battery Monitor Module (BMM) is responsible for monitoring the state of the vehicle's battery and ensuring that it is functioning correctly. It performs internal diagnostics to assess its own performance and communicates with the Body Control Module (BCM) via a Local Interconnect Network (LIN). The BCM then relays this information to the Engine Control Module (ECM) through a serial data connection. When the BMM detects an internal fault or an error in the communication of the alive rolling count—essentially a counter that tracks the number of messages sent—it triggers the P15FF code if this error persists for more than ten counts.
OBDII Code P15FF - Battery Monitor Sensor Signal Message Counter Incorrect
P15FF Code - Battery Monitor Sensor Signal Message Counter Incorrect

Common Causes of P15FF

  1. Faulty Battery Monitor Module
  2. Battery Monitor Module harness is open or shorted
  3. Battery Monitor Module circuit has a poor electrical connection
  4. Corrosion or damage at the battery terminals or connectors
  5. Software issues within the BCM or ECM affecting communication

Symptoms of P15FF

  1. Engine Light ON (or Service Engine Soon Warning Light)
  2. Frequent battery drain or difficulty starting the vehicle
  3. Electrical accessories malfunctioning or behaving erratically
  4. Inconsistent battery voltage readings
  5. Reduced fuel efficiency due to improper electrical management

How to Fix P15FF

  1. Perform a thorough diagnostic scan to confirm the P15FF code and check for related codes.
  2. Inspect the Battery Monitor Module and its wiring harness for any visible damage, corrosion, or loose connections.
  3. Test the Battery Monitor Module for proper functionality and replace it if found faulty.
  4. Check the battery terminals and connectors for corrosion and clean or replace as necessary.
  5. Reprogram or update the BCM or ECM software if communication issues are detected.

Cost to Fix P15FF

The cost to diagnose and repair the P15FF code typically ranges from $150 to $600, depending on the specific repairs needed. This includes parts such as a new Battery Monitor Module, which can cost between $100 and $300, along with labor charges that vary by location and shop type. Most shops charge between $80 and $150 per hour, with dealerships often being on the higher end of the scale and independent shops usually offering lower rates.

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Code P15FF Information for Specific Makes

  • P15FF Buick — Battery Monitor Sensor Signal Message Counter Incorrect
  • P15FF Cadillac — Battery Monitor Sensor Signal Message Counter Incorrect
  • P15FF Chevrolet — Battery Monitor Sensor Signal Message Counter Incorrect
  • P15FF GMC — Battery Monitor Sensor Signal Message Counter Incorrect
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.

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