On Nissan and Infiniti, B1018 is the occupant classification system reporting that its sensor has failed. That sensor is the pressure mat built into the passenger seat cushion, and it decides whether the front passenger airbag arms or stays suppressed. Mercedes-Benz gives B1018 to a different circuit entirely, so the make has to be settled before anyone opens a seat.
The occupant classification system on a Nissan or Infiniti reads how much weight is on the passenger seat and sorts it into a class: empty, a child or small occupant, or an adult. A pressure sensitive mat bonded into the bottom cushion does the measuring, an occupant classification control unit does the classifying, and the result goes to the air bag diagnosis sensor unit, which decides whether to arm the passenger bag.
Nissan separates that chain into its own codes, and the split is useful. B1018 is the sensor reporting failure. B1017 is the control unit. B1022 is a communication failure between the control unit and the diagnosis sensor unit. A B1018 on its own points at the seat, not at the module under the console.
Mercedes-Benz uses B1018 for an ignition circuit fault at R12/11, the left rear side airbag ignition squib. That is the firing circuit for the rear side bag on the left, and a fault there usually traces to the connector or the wiring rather than to the inflator.
Hardware on the Nissan and Infiniti side, and a circuit fault on the Mercedes side. Neither one is a deployment record. Nothing about B1018 says the vehicle was in a collision. What it does mean is that the front passenger airbag is working from a classification the system no longer trusts, so the behavior of the passenger airbag off lamp cannot be relied on while the code is stored.
No. A reset addresses stored crash data inside a control module, and B1018 is not crash data, so restoring the module changes nothing here. The repair is on the seat. When the mat has failed, the sensor side of the cushion gets replaced, and replacement units are listed under occupant classification sensors. Plan on a calibration step with a capable scan tool after the seat work, because the system has to be taught its new zero before the light goes out. If the vehicle also came out of a collision and the module locked with a stored record, that is a separate job through our airbag module reset.
The occupant classification reading of B1018 belongs to Nissan and Infiniti, and it turns up across models such as the Altima, Rogue, Murano, Leaf, and 370Z, along with the Infiniti cars that share the system. Mercedes-Benz assigns B1018 to the left rear side airbag squib circuit at R12/11, which sits in the R12 block alongside B1014 for the left front side airbag squib. Read it from the module that set it.
On a Nissan or Infiniti, start under the passenger seat before anyone quotes a cushion. Check the connectors for a pin that has backed out, corrosion, or a harness dragged by seat travel, and look for evidence of a spill in the cushion. If B1017 or B1022 is stored with B1018, the control unit and its wiring come into it as well.
On a Mercedes, pull the code with its component designation, then inspect the connector and wiring for the left rear side airbag before ordering an inflator. Replacement side bags are listed under seat airbags. When the part you need is not in the store, send us the year, model, and part number.
Related codes: B1017, B1022, B1023, B1014
Keep reading:
Code scope: Nissan, Infiniti, Mercedes-Benz. The same number can mean something different on another manufacturer, so match the code to your make before you act on it.
A reset clears stored crash data. A replacement part fixes a hardware fault. We have read these codes since the nineties and will tell you which one you are looking at.
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