Body, generic

B0054 Second Row Center Seat Belt Sensor

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B0054 is reserved for the buckle sensor of the middle seat in the second row. That position often has its buckle in a split bench or under a fold-down armrest, so the lead runs through moving seat parts. The rear warning required by FMVSS 208 S7.5(c) for vehicles made from September 2028 covers every rear designated seat, the middle one included. Ford's patent for rear belt monitoring counts latched belts once the car passes 3 mph with the doors shut and warns only when that count drops, so a passenger who changes seats is not flagged. The sensor itself is usually a Hall switch that detects the steel tongue in the buckle. No carmaker documents B0054 publicly; Mitsubishi's passenger code B0052 shows how such a buckle fault is set.

Likely causes

Lead of the centre buckle strained at the split bench or armrest hinge
Loose or corroded connector of the centre buckle
Faulty Hall switch in the centre buckle

Symptoms

  • Airbag or rear belt warning lamp on
  • Middle rear seat shown wrongly in the belt status display
  • Safety note: buckle plugs under the rear bench lie close to pretensioner wiring; only unplug them with the battery disconnected and the wait time observed

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€60–450
Time0.5–2.5 h

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

Parts involved

seat belt buckle switchsrs seat wiringsrs control module

Related codes

B0053B0055B0074

References: law.cornell.edu, patents.google.com, allegromicro.com, mitsubishitechinfo.com.