Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected that the voltage from part of the hybrid or electric vehicle's battery is lower than it should be.
The P0B79 code is triggered when the battery management system detects a low voltage condition in the voltage sensing circuit M of the hybrid or electric vehicle's battery pack.
The hybrid or electric vehicle's battery pack is monitored by a battery management system (BMS) that ensures optimal performance and safety. The BMS uses various sensors to monitor the voltage levels of different sections of the battery pack. Circuit M refers to one specific section or circuit of the battery pack. A 'low' condition indicates that the voltage in this circuit is below the expected range, which could be due to a sensor fault, wiring issue, or an actual problem with the battery cells.
• Check engine light on
• Reduced fuel economy
• Limited power or performance
• Faulty voltage sensor
• Damaged or corroded wiring/connectors
• Degraded battery cells
BMS: Battery Management System
Voltage Sensor: A device that measures the voltage level of a battery or battery pack
• Scan the vehicle for additional codes.
• Inspect the wiring and connectors for damage or corrosion.
• Test the voltage sensor for proper operation.
• Replace or repair damaged wiring or connectors.
• Replace the faulty voltage sensor.
• If necessary, replace the affected battery cells.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $1000
Moderate
• Toyota Prius
• Chevrolet Volt
• Nissan Leaf
• Regularly inspect battery connections.
• Perform routine maintenance checks.
• Avoid deep discharges of the battery.
Sensor Issue
• Avoid driving the vehicle until the issue is diagnosed.
• Consult a professional mechanic for an accurate diagnosis.
Battery and hybrid system components may be covered under extended warranties specific to hybrid and electric vehicles.
This code has become more common with the increased adoption of hybrid and electric vehicles, highlighting the importance of battery management systems.
Moderate – While the vehicle may still operate, it could lead to reduced performance and efficiency.
Ignoring this issue may lead to further damage to the vehicle's battery system, potentially resulting in costly repairs.
• Vehicle in 'Ready' mode
• Battery at normal operating temperature
The voltage sensor for circuit M is typically located within or near the hybrid/EV battery pack.
Q: Can I drive with a P0B79 code?
A: It's not recommended to drive with this code active, as it may lead to reduced vehicle performance and efficiency.
Q: How do I reset the P0B79 code?
A: After repairing the issue, the code can be reset using an OBD-II scanner.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.