OBD Guide

B1109

Diagnosis Sensor Unit

B1109 is an OBD-II diagnostic trouble code meaning: Diagnosis Sensor Unit. Common causes: damage to the wiring harness (harness), malfunction of the sensor diagnostic unit. Estimated repair cost: $56–167.

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

Symptoms

  • The Security System (SRS) indicator light is on.
  • Disabling airbags in the event of an accident
  • Malfunctions in the operation of belt pretensioners

Causes

  • Damage to the wiring harness (harness)
  • Malfunction of the sensor diagnostic unit
  • Short circuit or open circuit in the sensor circuit
  • Contact corrosion
  • Control unit software error

How to Fix

  1. Carry out diagnostics with an OBD-II scanner to read additional codes
  2. Check the integrity of the wiring harness (harness) and contacts
  3. Measure resistance in sensor circuits
  4. Check the status of the sensor diagnostic unit
  5. If necessary, replace faulty components or reflash the control unit

Related codes

FAQ

What does the B1109 code mean?

B1109 is an OBD-II diagnostic trouble code that indicates: Diagnosis Sensor Unit

What causes a B1109 error code?

The most common causes of B1109 include: Damage to the wiring harness (harness); Malfunction of the sensor diagnostic unit; Short circuit or open circuit in the sensor circuit; Contact corrosion.

How do I fix a B1109 diagnostic trouble code?

To fix B1109: Carry out diagnostics with an OBD-II scanner to read additional codes. Check the integrity of the wiring harness (harness) and contacts. Measure resistance in sensor circuits. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1109?

Do not drive — repair immediately

How much does it cost to fix B1109?

The estimated repair cost for B1109 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat