Powertrain, generic (extended)

P2E71 Hybrid/EV Battery Pack B Cell Thickness Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2E71 flags the thickness sensor circuit of pack B as reading too high. Not every swelling detector is analog: LG's module patent uses a panel that slides along a ramp until it touches a contact sensor, and a Lithium Energy and Power patent fits cells with insulated contact elements that close under pressure. Ford also describes a thin wire across a weakened cell wall that tears once the wall bulges, cutting the current through it. In such switch-type layouts an open circuit and a triggered sensor can look alike, so the controller needs a defined resting level to tell them apart. No manufacturer documents P2E71 publicly. Check connectors after pack B service first; low signal is P2E72.

Likely causes

Sensor connector in pack B not fully seated after battery work
Broken signal or ground wire to the sensor
Signal line shorted to a supply voltage

Symptoms

  • Hybrid or EV warning light
  • Possibly limited power or charging

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–2,500
Time1.5–8 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hybrid battery pack bhybrid battery pack b thickness sensorbms

Related codes

P2E70P2E72P2E73P2E6D

References: law.cornell.edu, image-ppubs.uspto.gov, image-ppubs.uspto.gov, image-ppubs.uspto.gov.