B1620CriticalSupplemental Restraint System (SRS) / airbag control unit

B1620: Airbag System Control Module (SRSCM) Internal Fault

2 vehicles · 2 makes · $250-$2,400 repair

Most Reported On

2010-2018Kia Forte 2006-2017Hyundai Accent

B1620 is an OBD-II diagnostic trouble code meaning “Airbag System Control Module (SRSCM) Internal Fault.” The Airbag Control Unit runs a self-diagnostic routine for roughly six seconds after the ignition is turned on. B1620 sets when that self-test reports an internal failure of the module itself. Hyundai has issued two separate remedies over time: Service Campaign TX8 reprograms the ACU because sufficient vibration during the diagnostic window (for example a door being slammed) could cause the module to erroneously detect an internal fault; Warranty Extension TXXQ / TSB 24-BE-014H lists B1620 as a genuine internal-failure code requiring ACU replacement on Accent (HC). This code is most commonly reported on 2010-2018 Kia Forte, and 2006-2017 Hyundai Accent, with repair costs ranging from $250 to $2,400.

Common Causes

1Genuine internal electronic failure of the ACU/SRSCM (remedy: ACU replacement per Warranty Extension TXXQ)

2Outdated B1620 diagnostic logic — vibration such as a slammed door during the post-ignition self-test falsely sets the code (remedy: ACU reprogramming per Service Campaign TX8)

3Water intrusion at the module location shorting the board

4Low or unstable supply voltage to the ACU during the self-test

Typical Repair Cost

$250 - $2,400

Based on 2 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.

Diagnostic Tools

B1620 does not use the standard P/B/C/U prefix. It may be a manufacturer-specific code, so verify that a scanner supports your exact year, model and module before buying.

Vehicles Affected (2)

Hyundai B1620 page →

AccentCritical

Passenger Occupant Classification Seat Sensor Mat Failure (Airbag / PASSENGER AIRBAG OFF Light)

2006-2017$250-$2,400

Kia B1620 page →

ForteCritical

Airbag Control Unit Electrical Fault - Airbags May Not Deploy in a Crash

2010-2018

FAQ

What does B1620 mean?

B1620 stands for "Airbag System Control Module (SRSCM) Internal Fault." The Airbag Control Unit runs a self-diagnostic routine for roughly six seconds after the ignition is turned on. B1620 sets when that self-test reports an internal failure of the module itself. Hyundai has issued two separate remedies over time: Service Campaign TX8 reprograms the ACU because sufficient vibration during the diagnostic window (for example a door being slammed) could cause the module to erroneously detect an internal fault; Warranty Extension TXXQ / TSB 24-BE-014H lists B1620 as a genuine internal-failure code requiring ACU replacement on Accent (HC).

What are the most common causes of B1620?

The most common causes of B1620 are: Genuine internal electronic failure of the ACU/SRSCM (remedy: ACU replacement per Warranty Extension TXXQ), Outdated B1620 diagnostic logic — vibration such as a slammed door during the post-ignition self-test falsely sets the code (remedy: ACU reprogramming per Service Campaign TX8), Water intrusion at the module location shorting the board, Low or unstable supply voltage to the ACU during the self-test. The specific cause varies by vehicle.

How much does it cost to fix B1620?

Repair costs for B1620 range from $250 to $2,400, depending on the vehicle and root cause.

Which vehicles are affected by B1620?

Au7o has documented B1620 across 2 vehicle models from 2 manufacturers: Hyundai, Kia.

Sources (7)

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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.