B1490 Hyundai occupant classification system fault

B1490 occupant classification system (OCS) defect (Hyundai)

B1490 in short

On Hyundai, B1490 is an occupant classification system (OCS) fault: the passenger seat sensor that decides whether the front passenger airbag is enabled. Dealers have replaced the seat cushion sensor and its module. The car usually drives, but the passenger airbag may not work as intended, so get it checked soon.

The occupant classification system measures what is on the front passenger seat and tells the airbag computer whether to allow the passenger airbag to deploy. When its readings or its module fail, the airbag computer stores a code and lights the airbag warning light.

Owner complaints on the Tucson, Accent and Azera show dealers reading B1490 as an OCS defect. On the Azera the dealer also found B1763 (OCS ECU defect) and advised replacing both the ECU and the passenger seat cushion. On the Tucson the light kept returning after parts were replaced.

Do not place anything on or under the passenger seat in an attempt to fix it, and do not disconnect seat wiring yourself; the seat harness is part of the airbag system.

Pick your make

B1490 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.

Most likely causes

  1. Occupant sensor in the passenger seat cushion

    Supported by vehicle data
    Why it ranks here
    Dealers replaced the passenger seat cushion assembly on a Tucson and advised it on an Azera for B1490.
    What would change this
    Rises if the OCS fault is current with an empty, correctly loaded seat. Falls if the fault clears after the seat module is addressed.

  2. OCS control unit

    Supported by vehicle data
    Why it ranks here
    On the Azera the dealer paired B1490 with B1763, an OCS ECU defect, and advised replacing the ECU.
    What would change this
    Rises if B1763 is also stored. Falls if only B1490 is stored and the cushion is replaced successfully.

What to test first

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

  1. Have a shop with an SRS-capable scan tool read the airbag module and note every stored code, current or history, and whether the fault is current.

    Best left to a shopTool: SRS-capable scan tool

    Warning:Airbag and seat belt pretensioner circuits can deploy if probed or disconnected incorrectly. Only a trained technician following the service manual should test them.

    • IfB1490 is current, alone or with an OCS ECU code such as B1763

      It meansThe occupant classification sensor or its module is the likely fault; the shop confirms with the OCS data.

      Points to: Occupant sensor in the passenger seat cushion

    • IfThe fault does not return after the shop clears it and checks the connectors

      It meansThe fault may have been intermittent. Do not assume it is gone; the airbag light should stay off through several drives.

Symptoms

  • Red airbag light that comes on and off at random
  • Passenger airbag indicator behaves wrongly or the light stays on after cars are loaded differently

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.

On your vehicle

Hyundai

No curated relationships for B1490 yet.

All Airbags and seat-belt restraints (SRS) codes

B1490 questions

Is it safe to drive with B1490 and the airbag light on?

The car usually still drives normally, but manufacturers say the airbags may not work as designed while the light is on. Get it checked soon and do not rely on the airbags until it is.

Sources and review

  1. 2023 Accord Owner's Manual: Airbag System Indicators — American Honda Motor Co.
  2. Camry Owner's Manual (OM06291U) — Toyota
  3. Nissan Supplemental Restraint Systems: damage analysis and repair using Diagnostic Trouble Codes (TechNews, Summer 2016) — Nissan North America ,
  4. NHTSA complaint ODI 10574858 (2013 Hyundai Tucson) — NHTSA Office of Defects Investigation
  5. NHTSA complaint ODI 11170467 (2013 Hyundai Azera) — NHTSA Office of Defects Investigation
  6. NHTSA complaint ODI 11083863 (2017 Hyundai Accent) — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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