OBD Guide
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B109B

License Plate Light

B109B is an OBD-II diagnostic trouble code meaning: License Plate Light. Common causes: burnt out backlight bulb, open or short circuit in wiring harness. Estimated repair cost: $6–33.

Severity
✅ Low
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$6–33 (est.)

Symptoms

  • License plate light does not work
  • Error message on the dashboard
  • Light fault warning

Causes

  • Burnt out backlight bulb
  • Open or short circuit in wiring harness
  • Malfunction of the lighting control unit
  • Poor contact in the connector

How to Fix

  1. Check the condition of the license plate lamp
  2. Inspect the wiring harness for damage
  3. Check the voltage at the lamp contacts
  4. Replace the lamp or LED module if necessary
  5. Check the operation of the lighting control unit

Related codes

B109AB109C

FAQ

What does the B109B code mean?

B109B is an OBD-II diagnostic trouble code that indicates: License Plate Light

What causes a B109B error code?

The most common causes of B109B include: Burnt out backlight bulb; Open or short circuit in wiring harness; Malfunction of the lighting control unit; Poor contact in the connector.

How do I fix a B109B diagnostic trouble code?

To fix B109B: Check the condition of the license plate lamp. Inspect the wiring harness for damage. Check the voltage at the lamp contacts. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B109B?

Yes, but get it checked soon

How much does it cost to fix B109B?

The estimated repair cost for B109B is $6–33. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat