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DTC codes / P0Bxx · Hybrid propulsion / P0B41

P0B41Hybrid/EV Battery Voltage Sense B Circuit Range/Performance

P0B41 indicates that the hybrid or electric vehicle battery pack's voltage sensing circuit B is reporting a voltage reading outside the range the control module expects, or that the circuit's performance is erratic. The battery energy control module compares this sense line against other voltage taps and flags the code when the signal is implausible, skewed, or intermittent.

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 message
  • Often no symptoms besides the warning light, with the vehicle driving normally
  • Reduced electric-only range or the engine starting more frequently than usual
  • A sudden drop into limp mode or refusal to enter EV drive mode
  • Inaccurate state-of-charge or battery voltage display on the dash
  • In rare cases, a no-start condition if the high-voltage contactors are inhibited

Common causes, most likely first

  1. A faulty voltage sense wire, chafed harness, or corroded connector pin at the battery pack
  2. A failed or drifting voltage sensing module or battery monitor unit
  3. A weak or failing cell group whose voltage tap reads out of range under load
  4. Loose or oxidized battery pack terminal or interconnector hardware
  5. Water intrusion or contamination in the battery pack connector or sense harness
  6. A software or calibration issue in the battery energy control module
  7. A failing battery energy control module itself, though this is less common

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P0B41 and any companion codes before clearing anything
  2. Inspect the battery pack sense harness and connectors for corrosion, chafing, or loose pins
  3. Measure the sense circuit B voltage at the module connector and compare it with a known-good tap
  4. Perform a battery pack voltage audit with a scan tool to see whether one cell group is skewed
  5. Check for water intrusion or debris in the pack connector area and dry or clean as needed
  6. Repair or replace the affected sense wire, connector, or sensing module and clear the code
  7. If the fault persists, reflash or replace the battery energy control module and re-verify live data

What the voltage sense code hides

  • A single skewed cell group can set P0B41 while the pack still delivers normal power, so the code often points to a sense-line problem rather than a failed pack.
  • Technicians frequently replace the battery energy control module when the real fault is a corroded pin in the sense connector, so always load-test the circuit before condemning the module.
  • The code can be intermittent and only appear under high-current discharge or regen braking, which means a static voltage check at rest may look perfectly normal.
  • A loose interconnector or terminal hardware can cause a voltage drop that mimics a failed sense circuit, so torque checks belong in the diagnostic sequence.
  • Companion codes for other voltage sense circuits or cell imbalance often reveal whether the fault is a shared harness issue or a single tap problem.

Can I keep driving with P0B41?

The vehicle is usually safe to drive to a workshop because the fault is a sensing issue rather than an immediate high-voltage hazard, but avoid aggressive acceleration, heavy regen braking, and long trips until it is diagnosed. If the hybrid system warning light flashes or the car enters limp mode, stop driving and arrange a tow.

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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