OBD Guide
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B21DD

System Voltage Signal

B21DD is an OBD-II diagnostic trouble code meaning: System Voltage Signal. Common causes: poor contact in connectors, wiring harness damage. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • Airbag light is on
  • Restraint system inactive

Causes

  • Poor contact in connectors
  • Wiring harness damage
  • Unstable voltage in the on-board network
  • Airbag control module malfunction

How to Fix

  1. Check the voltage in the on-board network
  2. Inspect the connectors and wiring harness of the passive restraint system
  3. Check the integrity of the squibs and other components
  4. If necessary, replace the airbag control module

Related codes

B2100B2110B2130

FAQ

What does the B21DD code mean?

B21DD is an OBD-II diagnostic trouble code that indicates: System Voltage Signal

What causes a B21DD error code?

The most common causes of B21DD include: Poor contact in connectors; Wiring harness damage; Unstable voltage in the on-board network; Airbag control module malfunction.

How do I fix a B21DD diagnostic trouble code?

To fix B21DD: Check the voltage in the on-board network. Inspect the connectors and wiring harness of the passive restraint system. Check the integrity of the squibs and other components. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B21DD?

Do not drive — repair immediately

How much does it cost to fix B21DD?

The estimated repair cost for B21DD is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat