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DTC codes / P2Exx · Hybrid propulsion / P2E6D

P2E6DHybrid/EV Battery Pack A Cell Thickness Sensor Circuit High

P2E6D indicates that the battery energy control module (BECM) has detected an abnormally high voltage on the cell thickness sensor circuit for hybrid/EV battery pack A. The sensor monitors physical swelling or expansion of the battery cells, and a high signal typically means an open circuit, a short to voltage, or a sensor fault rather than actual cell swelling.

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

Symptoms you may notice

  • Illumination of the check engine light or hybrid system warning light, often with no other noticeable symptoms.
  • Reduced electric-only range or forced engine operation if the vehicle enters a fail-safe mode.
  • A message on the dash indicating a hybrid battery fault or service required.
  • In rare cases, a burning smell or visible battery pack deformation if the sensor is responding to actual cell swelling.
  • Intermittent warning light activation over bumps or during temperature changes if the circuit has a loose connection.

Common causes, most likely first

  1. Open circuit in the cell thickness sensor signal wire, such as a broken wire or disconnected connector.
  2. Short to voltage on the sensor signal circuit, often from chafed wiring harness insulation.
  3. Faulty cell thickness sensor internal failure, causing a fixed high resistance or open output.
  4. Corroded or loose electrical connector pins at the sensor or battery pack interface.
  5. Battery energy control module (BECM) internal fault misreading the sensor input.
  6. Actual battery cell swelling that has pushed the sensor beyond its normal range, though this is less common than circuit faults.

How to diagnose and fix it

  1. Inspect the cell thickness sensor connector and wiring for damage, corrosion, or loose pins, and repair as needed.
  2. Measure the sensor signal voltage with a multimeter and compare to the manufacturer's specification to confirm the high condition.
  3. Disconnect the sensor and check for an open or short in the signal circuit using a wiring diagram and continuity tests.
  4. Substitute a known-good sensor or simulate the signal with a resistor box to see if the code changes, isolating the sensor from the circuit.
  5. Check the BECM connectors and grounds for integrity, and verify power and ground supplies to the module.
  6. If the circuit and sensor test good, follow the manufacturer's diagnostic flow for BECM testing or reprogramming.
  7. Clear the code after repairs and perform a road test to confirm the fault does not return.

High voltage does not always mean swelling

  • A high signal on a cell thickness sensor circuit is most often caused by an open circuit or a short to voltage, not by actual battery cell expansion.
  • Technicians sometimes replace the battery pack unnecessarily when the real problem is a chafed wire or corroded connector in the sensor circuit.
  • The cell thickness sensor is part of the high-voltage battery assembly, so safe servicing requires de-energizing the high-voltage system and following manufacturer procedures.
  • In some vehicles, the BECM may set this code if the sensor signal is out of range during self-test, even if the sensor later tests normal, so intermittent faults need wiggle tests and freeze-frame data review.
  • Related codes for other cell thickness sensors or battery voltage sensors may also be present, indicating a shared wiring or module issue rather than a single sensor failure.

Can I keep driving with P2E6D?

If the only symptom is a warning light and the vehicle drives normally, you can drive cautiously to a service location, but avoid aggressive acceleration or charging until diagnosed. If the vehicle enters a reduced-power mode or shows a battery fault message, 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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