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DTC codes / P0Bxx · Hybrid propulsion / P0B98

P0B98Hybrid/EV Battery Voltage Sense S Circuit High

P0B98 indicates that the hybrid or electric vehicle battery pack control module has detected an abnormally high voltage on the dedicated voltage sensing circuit for one specific battery module, often labeled 'S' in the manufacturer's wiring diagrams. This high signal suggests a wiring fault, a poor connection, or an internal issue within the battery pack that is causing the voltage reading to exceed the expected range.

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, especially if the high voltage is intermittent
  • Reduced electric-only range or the vehicle refusing to enter EV mode
  • Possible reduced engine power or limp mode if the fault triggers a safety shutdown
  • In rare cases, a burning smell or slight swelling of the battery pack if a cell is failing

Common causes, most likely first

  1. Corroded, loose, or damaged voltage sense wire between the battery module and the control module
  2. Faulty voltage sensing circuit inside the battery pack control module
  3. High resistance in the sense circuit connector or terminal
  4. Internal short or cell imbalance within the battery module causing an abnormally high voltage reading
  5. Water intrusion or contamination in the battery pack connector
  6. Software glitch in the battery control module requiring recalibration or update

How to diagnose and fix it

  1. Inspect the voltage sense wiring and connectors for damage, corrosion, or looseness, and repair as needed
  2. Measure the actual voltage at the battery module terminals and compare it with the scan tool reading to verify the fault
  3. Perform a resistance test on the sense circuit to check for high resistance or open circuits
  4. Check for technical service bulletins (TSBs) or software updates for the battery control module
  5. If wiring and connections are good, test the battery control module with a known-good unit or perform a module reset
  6. Replace the battery module if internal cell imbalance or short is confirmed
  7. Clear the diagnostic trouble codes and perform a road test to verify the repair

Voltage Sense Circuit High: Don't Assume the Battery

  • A high voltage sense code is frequently caused by a simple loose connector or chafed wire, not a failing battery pack, so always inspect the harness first.
  • The 'S' circuit may refer to a specific module in a multi-module pack, and misidentifying which module can lead to replacing the wrong component.
  • In some vehicles, a weak 12-volt auxiliary battery can cause erratic behavior in the hybrid control module and set false voltage sense codes.
  • After repairing the circuit, the battery control module may require a learn or calibration procedure to clear the code permanently.
  • This code can be set by a temporary voltage spike during charging or discharging, so check for pending codes and freeze-frame data before condemning parts.

Can I keep driving with P0B98?

If the vehicle drives normally and the warning light is steady, you can drive cautiously to a service center, but avoid aggressive acceleration or high-speed driving. If the light is flashing or the vehicle enters limp mode, stop safely and have it towed to avoid damaging the hybrid battery pack.

Tools that help

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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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