OBD Guide

B1125

Diagnosis Sensor Unit

B1125 is an OBD-II diagnostic trouble code meaning: Diagnosis Sensor Unit. Common causes: damage to the wiring harness (harness), corrosion of contacts in the diagnostic circuit. 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 fault message on the instrument panel
  • The safety system may not work in an accident

Causes

  • Damage to the wiring harness (harness)
  • Corrosion of contacts in the diagnostic circuit
  • Malfunction of the sensor diagnostic unit
  • Problems with squibs or shock sensors

How to Fix

  1. Check the integrity of the passive restraint system wiring harness
  2. Inspect contacts and connectors for corrosion
  3. Scan the system for other related error codes
  4. Test the sensor diagnostic unit with specialized equipment
  5. If necessary, replace the faulty component

Related codes

FAQ

What does the B1125 code mean?

B1125 is an OBD-II diagnostic trouble code that indicates: Diagnosis Sensor Unit

What causes a B1125 error code?

The most common causes of B1125 include: Damage to the wiring harness (harness); Corrosion of contacts in the diagnostic circuit; Malfunction of the sensor diagnostic unit; Problems with squibs or shock sensors.

How do I fix a B1125 diagnostic trouble code?

To fix B1125: Check the integrity of the passive restraint system wiring harness. Inspect contacts and connectors for corrosion. Scan the system for other related error codes. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1125?

Do not drive — repair immediately

How much does it cost to fix B1125?

The estimated repair cost for B1125 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat