Powertrain, generic (extended)

P2E8B Proximity Detection Circuit B Intermittent/Erratic

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2E8B describes a plug-detection signal on circuit B that drops out or jumps for moments, so the car sees a connector appear and vanish although nobody touched it. The consequences follow from the purpose of the line: under SAE J1772 the proximity state is what lets the vehicle stop drawing current before the plug is released and block driving off while connected, so a flickering signal can end charging for no visible reason or let a drive lock come and go. In Lear's patented design the same line also wakes the charger, so glitches can rouse it needlessly. No manufacturer documents P2E8B. Mercedes describes the classic cause for circuit A on the smart with 22 kW charger: loose low-voltage plugs that act up only with warm or cold parts, alongside P0D5800/P0D5900. Hard faults are P2E89/P2E8A.

Likely causes

Loose low-voltage connector on the proximity line
Worn proximity contact in inlet B or on the cable plug
Chafed wire with intermittent contact to ground
Moisture in the inlet after rain or washing

Symptoms

  • Charging stops and restarts at random
  • Cable-connected message appears and disappears
  • Fault more frequent at the start or end of charging

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–800
Time0.3–3 h

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

Parts involved

proximity detection bcharge inlet bwiring harness

Related codes

P2E87P2E88P2E89P2E8AP0D5A

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