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DTC codes / P0Bxx · Hybrid propulsion / P0B67

P0B67Hybrid/EV Battery Voltage Sense I Circuit Intermittent/Erratic

P0B67 is set when the hybrid or electric vehicle battery pack controller detects an intermittent or erratic voltage signal from one of the battery cell voltage sense circuits, designated circuit I. The computer expects a stable voltage reading from that sense line, and when the signal jumps, drops out, or behaves erratically, it stores this code to flag a problem with the sensing circuit rather than a confirmed cell failure.

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 with no other noticeable symptoms.
  • Intermittent loss of hybrid battery assist or reduced electric-only operation.
  • A sudden drop in state of charge or erratic battery gauge readings.
  • The vehicle may enter a reduced power or limp mode, especially under load.
  • In some cases, the engine may start more frequently or the hybrid system may refuse to engage.
  • Often no symptoms besides the warning light, particularly if the intermittent fault is not currently active.

Common causes, most likely first

  1. A loose, corroded, or damaged electrical connector at the battery voltage sense harness or at the battery pack controller.
  2. Chafed, pinched, or broken wiring in the voltage sense circuit, often due to vibration or routing issues.
  3. A faulty voltage sense circuit board or sensing module within the battery pack.
  4. Internal battery pack controller fault causing erratic signal processing.
  5. High resistance or intermittent open in the sense wire due to a poor terminal crimp or corrosion.
  6. A failing battery cell or module that causes voltage fluctuations, though the code specifically flags the sense circuit.
  7. Water intrusion or contamination in the battery pack connector or harness, leading to intermittent signals.

How to diagnose and fix it

  1. Inspect the battery pack voltage sense harness and connectors for looseness, corrosion, or damage; clean and reseat as needed.
  2. Perform a wiggle test on the sense circuit wiring while monitoring live voltage data to reproduce the intermittent fault.
  3. Check for technical service bulletins (TSBs) or manufacturer-specific diagnostic procedures for the voltage sense circuit.
  4. Measure resistance and voltage drop across the sense circuit from the battery cell to the controller, comparing with known good circuits.
  5. If the sense circuit is integrated into a battery module, test the module and replace if faulty.
  6. Repair or replace damaged wiring, terminals, or connectors in the voltage sense circuit.
  7. If all external circuits test good, diagnose or replace the battery pack controller or sensing module as required.

Sense circuit faults often mimic cell failure

  • A loose connector or chafed wire is far more common than a failed battery cell, so always inspect the harness before condemning the pack.
  • The code can be set by a momentary glitch that does not affect drivability, so clearing it and test-driving may reveal whether it returns.
  • Some vehicles use a single sense line for multiple cells, so an erratic signal on circuit I can affect the reported voltage of several cells, confusing diagnosis.
  • High-voltage battery sense circuits are sensitive to resistance changes; a terminal that looks clean may still have excessive resistance under vibration.
  • Replacing the battery pack without diagnosing the sense circuit is an expensive misstep that this code is designed to prevent.

Can I keep driving with P0B67?

If the warning light is on but the vehicle drives normally, you can usually continue driving to a service center, but avoid heavy acceleration or long trips until diagnosed. If the vehicle enters limp mode or shows erratic battery behavior, stop driving and have it towed to avoid potential high-voltage hazards.

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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