P0B3B: Hybrid/EV Battery Voltage Sense A Circuit

Voltage sense A to Z and beyond are the cell or cell-group sense channels of the battery monitoring electronics, unlike the pack voltage sense codes P0ABA and P0B14 ff, which measure the whole pack. P0B3B is the circuit code for channel A. GM uses it in the battery energy control module as an open sense line check: neighbouring cell readings differ by 1.3 V or more, or a cell reads under 36 mV with balancing on, or a splice reads over 0.1 V (bus bar 0.5 V), for 0.6 s; Type A, one trip. Ford stores P0B3B with other open-line codes on the 2019-2020 Fusion PHEV and 2023 Mach-E; Honda's 2014-2015 Accord Hybrid used it for a cell voltage sensor fault caused by inverter noise.

Symptoms

• MIL or powertrain warning, Stop Safely Now message possible
• No start or no charging
• Fail-safe EV mode with limited speed and sudden loss of power

Most likely causes

• Open cell sense line, splice or bus bar connection inside the pack
• Intermittent fault in the flexible printed circuit to the battery controller (Ford Mach-E)
• Sensor software misreading inverter noise, fixed by update (Honda)
• Internal failure of the traction battery requiring pack replacement (Ford Fusion PHEV)

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. Make sure the battery cooling air intake is clean
3. Check the 12 V auxiliary battery, which can also trigger warnings
4. Leave any high-voltage measurements to a specialized repair shop

Good to know

• It can trigger limp mode.
• It affects emissions.

What each character of P0B3B means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• B: Subsystem depends on the code range
• 3B: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0B3B?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0B3B?

The most common causes are: open cell sense line, splice or bus bar connection inside the pack; intermittent fault in the flexible printed circuit to the battery controller (Ford Mach-E); sensor software misreading inverter noise, fixed by update (Honda).

Related codes

• P0B3CHybrid/EV Battery Voltage Sense A Circuit Range/Performance
• P0B3DHybrid/EV Battery Voltage Sense A Circuit Low
• P0B3EHybrid/EV Battery Voltage Sense A Circuit High
• P0B3FHybrid/EV Battery Voltage Sense A Circuit Intermittent/Erratic
• P0B40Hybrid/EV Battery Voltage Sense B Circuit
• P0ABAHybrid/EV Battery Pack Voltage Sense A Circuit

Sources

• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
• static.nhtsa.gov: MC 10232489 0001
• static.nhtsa.gov: MC 11005840 0001
• static.nhtsa.gov: MC 10108683 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.