Body, generic

B00E4 Second Row Right Seat Belt Pretensioner C Deployment Control

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B00E4 belongs to the outboard seat on the right in the back and its C-stage tensioner. Mercedes-Benz uses it in that sense: every version of LI54.21-P-070658 seen here (December 2019 to June 2020) lists B00E413 as an open in the squib of the tensioning retractor at the rear right. The topic blames higher resistance at the SRS unit connector rather than the tensioner and tells technicians to trace the wire, reseat the plugs and replace the unit only on recurrence. The retractor sits behind the rear trim or in the seat and winds the webbing back when fired, as GM's rescue guide and Joyson explain. No public bulletin from another maker cites B00E4. While the code is stored, the airbag lamp or SRS message stays on.

Likely causes

Poor contact at the SRS control unit plug (Mercedes A-Class/CLA/GLB)
Plug at the right rear retractor loose after trim removal
Airbag control unit itself faulty (fault returns after reconnecting)
Squib in the right rear retractor open

Symptoms

  • SRS message or airbag lamp permanently displayed
  • Right rear passenger loses shoulder-belt tensioning
  • Safety note: pyrotechnic tensioner – only work on it with the battery disconnected and after the wait time, ideally at a specialist workshop

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–900
Time0.3–2.5 h

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

Parts involved

second row right pretensioner csquib circuitsrs control module

Related codes

B00E3B00E5B0075B007CB0055

References: static.nhtsa.gov, static.nhtsa.gov, gmstc.com, joysonsafety.com.