Powertrain, generic (extended)

P2E72 Hybrid/EV Battery Pack B Cell Thickness Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2E72 means the pack B thickness sensor reports a signal below its valid floor. On a bridge-type strain gauge, the output is a small fraction of the excitation voltage that grows with strain, so losing that excitation or shorting a bridge leg to ground pulls the reading towards zero. Capacitive designs, such as a patented pressure-sensitive QTC sensor coated with indium tin oxide, depend on a measuring module that can fail the same way. LG's piezo elements in the cell gaps only output voltage under pressure, so a short across them hides real expansion. No manufacturer documents P2E72 publicly. CARB demands separate codes for low and high faults; the high side of this circuit is P2E71, pack A's low code P2E6E.

Likely causes

Signal line or sensor shorted to ground inside pack B
Sensor excitation or reference supply lost
Fault in the measuring circuit of the battery monitoring module

Symptoms

  • Hybrid or EV warning light
  • Power or charging may be reduced as a precaution

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

P2E70P2E71P2E73P2E6E

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