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DTC codes / P0Bxx · Hybrid propulsion / P0B44

P0B44Hybrid/EV Battery Voltage Sense B Circuit Intermittent/Erratic

P0B44 indicates that the hybrid or electric vehicle battery pack's voltage sensing circuit B is reporting an intermittent or erratic signal to the battery energy control module. The computer detects this when the voltage reading from that specific sense line jumps, drops out, or becomes inconsistent with the other cell voltage sensors, often within a short time window.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the hybrid system warning light or service vehicle soon light
  • Often no symptoms besides the warning light, especially if the erratic signal is brief
  • Reduced electric-only range or the vehicle refusing to enter EV mode
  • Intermittent loss of power or hesitation under acceleration
  • The hybrid system may disable and force the vehicle into limp mode
  • A message on the dash indicating a hybrid battery fault or reduced power

Common causes, most likely first

  1. Loose, corroded, or damaged wiring or connector pins at the voltage sense harness for circuit B
  2. Faulty voltage sense wire within the battery pack harness, often due to chafing or heat damage
  3. Internal failure of the battery energy control module's voltage sensing circuit
  4. Poor connection at the battery pack terminal or inter-cell bus bar affecting the sense point
  5. Water intrusion or contamination in the battery pack connector causing intermittent shorts
  6. A failing cell group that causes voltage fluctuations only under load, triggering the sense circuit intermittently

How to diagnose and fix it

  1. Inspect and clean the voltage sense connector and pins for circuit B at the battery pack, looking for corrosion or looseness
  2. Perform a wiggle test on the sense harness while monitoring live voltage data to reproduce the intermittent signal
  3. Check the sense wire for continuity and resistance from the battery pack connector to the control module, repairing any opens or high resistance
  4. Compare the voltage reading from circuit B with adjacent sense circuits and a multimeter measurement at the cell group to isolate a sensor versus cell issue
  5. If the harness and connections are good, substitute a known-good battery energy control module and retest
  6. Clear the code and perform a hybrid battery learn or calibration procedure if required by the manufacturer
  7. Verify the repair by test-driving under various loads and confirming no return of the intermittent code

Why an intermittent sense code misleads

  • A loose ground connection at the battery pack can cause erratic voltage readings on multiple sense circuits, not just B, so always check grounds before condemning the control module.
  • The code often sets only after a specific number of erratic events within a drive cycle, so a single glitch may not store it; this makes intermittent harness faults hard to catch without live data logging.
  • A failing cell that only acts up under high load can mimic a sense circuit fault, so load-test the battery pack while watching individual cell voltages before replacing any electronics.
  • Technicians sometimes replace the battery energy control module only to find the real problem is a chafed wire behind the pack, so always perform a thorough harness inspection first.
  • This code can be set by a low 12-volt auxiliary battery causing unstable reference voltage to the control module, so check the conventional battery and charging system before diving into the high-voltage side.

Can I keep driving with P0B44?

You can usually continue driving if the warning light is steady and the vehicle behaves normally, but avoid heavy acceleration or long trips until the fault is diagnosed. If the hybrid system disables or the car enters limp mode, pull over safely and arrange a tow to prevent further damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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