OBD Guide
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B3978

Incorrect Environmental Identifier Received from Inflatable Restraint Sensing and Diagnostic Module

B3978 is an OBD-II diagnostic trouble code meaning: Incorrect Environmental Identifier Received from Inflatable Restraint Sensing and Diagnostic Module. Common causes: security module firmware mismatch, damage to the wiring harness between modules. Estimated repair cost: $167–444.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$167–444 (est.)

Symptoms

  • Airbag light is on
  • The safety system may not work in an accident
  • The error does not disappear after a scanner reset

Causes

  • Security module firmware mismatch
  • Damage to the wiring harness between modules
  • Incorrect replacement of security components
  • Corrosion or poor contact in connectors
  • SDM module failure

How to Fix

  1. Diagnostics of the communication bus using an oscilloscope
  2. Checking software versions of all security modules
  3. Updating or flashing modules
  4. Checking the integrity of the wiring harness
  5. Replacement of faulty components if necessary

Related codes

B0028B0051U0121

Error B3978 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the B3978 code mean?

B3978 is an OBD-II diagnostic trouble code that indicates: Incorrect Environmental Identifier Received from Inflatable Restraint Sensing and Diagnostic Module

What causes a B3978 error code?

The most common causes of B3978 include: Security module firmware mismatch; Damage to the wiring harness between modules; Incorrect replacement of security components; Corrosion or poor contact in connectors.

How do I fix a B3978 diagnostic trouble code?

To fix B3978: Diagnostics of the communication bus using an oscilloscope. Checking software versions of all security modules. Updating or flashing modules. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B3978?

Do not drive — repair immediately

How much does it cost to fix B3978?

The estimated repair cost for B3978 is $167–444. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat