B1018: Passenger seat occupant sensor mat malfunction (Nissan)

Occupant classification system (OCS) sensor mat fault

Severity: Inspect soon

The airbag light means the system has found a fault, and owner's manuals say to have it checked promptly because the airbags may not work as designed; this code concerns the sensor that decides whether the passenger airbag should deploy.

Safety-critical system: explanation only, no DIY steps. Source: how we rate severity

B1018 in short

On Nissan models, B1018 means the airbag computer found a fault in the front passenger seat's occupant sensor mat, which tells it who is sitting there. The airbag light comes on and the passenger airbag may not work as designed. Have a dealer check it soon, and never probe airbag wiring yourself.

Nissan's occupant classification system uses a sensor mat and a small control unit inside the front passenger seat cushion. Together they tell the airbag computer whether the seat is empty or occupied, so it can decide whether the passenger airbag should deploy.

Nissan's training material lists B1018 as the code for a malfunctioning sensor mat, with B1017, B1020 and B1021 for the OCS control unit and B1022 for lost communication with the airbag computer. Nissan says not to take the parts apart: the repair is the complete passenger seat cushion assembly.

Nissan and Infiniti also recalled many 2013–2017 vehicles because the OCS could wrongly treat an occupied seat as empty and switch the passenger airbag off. Those recalls do not name B1018, but a dealer will check them for your VIN. We could not verify Infiniti's meaning for this code.

Pick your make

B1018 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

B1018 on Nissan

Most likely causes

Cause 1: Occupant sensor mat in the passenger seat cushion
Supported by vehicle data
Why it ranks here
Nissan's own description of B1018 is a malfunctioning OCS sensor mat, and its repair is the passenger seat cushion assembly that contains it.
What would change this
Rises if B1018 stays current after the seat is cleared and the code is cleared. Falls if an OCS software recall is open and fixes the light.
Cause 2: Occupant classification software covered by a recall
Possible — needs testing
Why it ranks here
Recalls 14V-138 and 16V-244 update or reprogram the OCS and airbag computer on many 2013–2017 Nissan and Infiniti models because the system could misclassify the passenger. The recall records do not name B1018, so this is a check rather than a confirmed cause.
What would change this
Rises if a dealer finds one of these recalls open on your VIN. Falls if the recall work was already done.
Cause 3: Objects, liquid or pressure on the passenger seat upsetting the sensor
Possible — needs testing
Why it ranks here
Honda's manual warns that spilled liquid or objects under the seat can stop the passenger sensors working properly, and Toyota warns that kicking the passenger seat can make the system report a fault. These are general warnings, not Nissan findings for B1018.
What would change this
Rises if the light goes out and stays out once the seat is cleared and dried. Falls if the code returns with the seat empty and dry.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Have the airbag codes read with a scan tool that can talk to the airbag module, and note every code stored.
Low riskTool: scan tool with airbag (SRS) access
- IfB1018 is the only airbag code
  It meansNissan points to the passenger seat sensor mat, but check for recalls first.
  Go to step 2
- IfB1017, B1020, B1021 or B1022 is stored too
  It meansNissan links these to the OCS control unit or its link to the airbag computer, which are part of the same seat cushion assembly.
  Points to: Occupant sensor mat in the passenger seat cushion
Step 2: Give your VIN to a Nissan or Infiniti dealer, or look it up on NHTSA's recall site, and ask whether recall 14V-138 or 16V-244 is open.
Low risk
- IfA recall is open
  It meansHave the recall done first; it is free.
  Points to: Occupant classification software covered by a recall
- IfNo recall is open
  It meansRule out anything on or under the seat.
  Go to step 3
Step 3: Remove anything stored on or under the front passenger seat and dry any spilled liquid, then see whether the airbag light still comes on after the next restart.
Low risk
- IfThe light goes out and stays out
  It meansSomething on or under the seat was likely upsetting the sensor.
  Points to: Objects, liquid or pressure on the passenger seat upsetting the sensor
- IfThe light stays on
  It meansThe system needs a dealer diagnosis.
  Go to step 4
Step 4: Have a Nissan dealer or trained technician run the airbag diagnosis with Nissan's diagnostic tool.
Best left to a shopTool: Nissan CONSULT diagnostic tool
Warning:Never probe airbag connectors or wiring with a test light or meter, and never unplug them yourself. Nissan warns that airbags and pretensioners can still deploy after the ignition is off, and that test equipment must not be used on airbag circuits unless the service manual calls for it. Leave this to a dealer or trained technician.
- IfThe technician confirms B1018 is current
  It meansNissan's repair is the passenger seat cushion assembly.
  Points to: Occupant sensor mat in the passenger seat cushion

Symptoms

Airbag warning light stays on after the engine starts
Passenger airbag status light shows the airbag off with an adult in the seat

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

Front passenger seat cushion assembly:Nissan replaces the whole cushion assembly, which holds the sensor mat and OCS control unit, rather than taking it apart. Recall work is free at a dealer. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Nissan

2012 · Altima
Supported by vehicle data
Nissan's training material uses the 2012 Altima to show the OCS codes: B1018 is the sensor mat, and the repair is the passenger seat cushion assembly.
2013–2014 · Altima
Possible — needs testing
Recall 14V-138 updated the OCS software on these models because an occupied seat could be read as empty. The recall does not name B1018; ask a dealer whether it is open on your VIN.
Related recall campaigns: 14V138000

All Airbags and seat-belt restraints (SRS) codes

B1018 questions

Can an adult sit in the front passenger seat with B1018?

If the passenger airbag status light shows the airbag off with an adult seated, Honda's manual says not to let them ride there. Move them to the back seat until the system is fixed.

Can the sensor mat be replaced on its own?

Nissan says no: its repair for the OCS codes is the complete passenger seat cushion assembly, which should not be taken apart.

Sources and review

2023 Accord Owner's Manual: Airbag System Indicators — American Honda Motor Co.
Camry Owner's Manual (OM06291U) — Toyota
Nissan Supplemental Restraint Systems: damage analysis and repair using Diagnostic Trouble Codes (TechNews, Summer 2016) — Nissan North America , September 1, 2016
Recall 14V-138: occupant classification system may not detect an occupied passenger seat — Nissan North America / NHTSA (via vehiclesafetyrecalls.com) , March 25, 2014
Recall 16V-244: passenger frontal airbag may not deploy due to occupant classification error — Nissan North America / NHTSA (via vehiclesafetyrecalls.com) , April 26, 2016
NHTSA investigation EA15-004: occupant classification system failure (Nissan) — NHTSA (via carcomplaints.com)
NTB19-071C: DTC B00A0-00 stored (amended) — Nissan North America / NHTSA , March 9, 2023
TSB-BOD-130: Front passenger OCS sensor mat diagnosis and replacement (2007–2009 Spectra) — Kia America / NHTSA , February 26, 2016

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Inspect soon

Pick your make

Most likely causes

Cause 1: Occupant sensor mat in the passenger seat cushion

Cause 2: Occupant classification software covered by a recall

Cause 3: Objects, liquid or pressure on the passenger seat upsetting the sensor

What to test first

Step 1: Have the airbag codes read with a scan tool that can talk to the airbag module, and note every code stored.

Step 2: Give your VIN to a Nissan or Infiniti dealer, or look it up on NHTSA's recall site, and ask whether recall 14V-138 or 16V-244 is open.

Step 3: Remove anything stored on or under the front passenger seat and dry any spilled liquid, then see whether the airbag light still comes on after the next restart.

Step 4: Have a Nissan dealer or trained technician run the airbag diagnosis with Nissan's diagnostic tool.