P0B44: Hybrid/EV Battery Voltage Sense B Circuit Intermittent/Erratic

P0B44 is the J2012 slot for a cell voltage channel B whose reading jumps or drops out for short moments rather than failing permanently. No manufacturer documents P0B44 publicly. For orientation, GM's 2019 tables check channel B for open sense lines (P0B40), frozen values compared with the other cells (P0B41) and fixed limits of 0.2 V and 4.8 V (P0B42, P0B43); an erratic monitor would add a test for implausible steps between samples. CARB requires the storage system's voltage sensors to be monitored as inputs and faults to be pinpointed to the smallest replaceable unit. Typical causes are vibration-loosened cell taps and connectors on the monitoring board. Warnings may come and go with driving conditions.

Symptoms

• MIL or hybrid warning that comes and goes
• Occasional loss of electric drive or assist

Most likely causes

• Loose or cracked cell tap connection
• Fretting or vibration damage at the monitoring board connector
• Electrical noise from inverter or motor coupling into the sense lines

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. Gently move the wiring with the engine running and watch whether the reading changes.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. 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 P0B44 means

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

Frequently asked questions

Can I keep driving with code P0B44?

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 P0B44?

The most common causes are: loose or cracked cell tap connection; fretting or vibration damage at the monitoring board connector; electrical noise from inverter or motor coupling into the sense lines.

Related codes

• P0B40Hybrid/EV Battery Voltage Sense B Circuit
• P0B41Hybrid/EV Battery Voltage Sense B Circuit Range/Performance
• P0B42Hybrid/EV Battery Voltage Sense B Circuit Low
• P0B43Hybrid/EV Battery Voltage Sense B Circuit High
• P0B3FHybrid/EV Battery Voltage Sense A Circuit Intermittent/Erratic
• P0B18Hybrid/EV Battery Pack Voltage Sense B Circuit Intermittent/Erratic

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics

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.