Body, generic

B00C4 Passenger Seat Occupant Classification Sensor E

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B00C4 stands for the fifth and last passenger seat classification input; no public carmaker source uses it. Two field cases show what goes wrong besides wiring. Mazda found on 2016–2019 models that a phone, tablet or laptop lying on an empty passenger seat could make the system see a person: the passenger belt warning came on while PASS AIRBAG OFF stayed dark, and the advice was simply to keep devices off the seat. Land Rover quarantined 2025 Range Rover Sport SV cars because the OCS modules had been calibrated with the wrong weight, so the bag might not be switched off for a child seat as FMVSS 208 demands; new modules took 1.1 h. Calibration and plausibility therefore matter as much as the sensor. With B00C4 stored, the airbag lamp is lit and E is not trusted.

Likely causes

Classification module calibrated wrongly or not at all after replacement
Open or high-resistance contact on the lead to input E
Electronic devices or other objects on the seat confusing the sensing

Symptoms

  • Airbag warning lamp on
  • Passenger belt warning or airbag status lamp does not match who or what is on the seat
  • Safety note: passenger airbag may stay enabled for a child seat; disconnect only de-energised, calibrate with the maker's procedure after any module change, specialist workshop only

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–1,200
Time0.5–3 h

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

Parts involved

passenger classification sensor esrs seat wiringoccupant classification module

Related codes

B00C3B00C0B00A0B00D1B00B4

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.