Airbags

B0103 — Front Impact Sensor Communication Fault

Severity: high Drive with care, to a shop

What B0103 means

The SRS (airbag) control module constantly monitors the front impact sensors mounted at the front of the body. B0103 means communication with one of these sensors was lost or its signal is invalid. While the fault is active, the system may disable part of its protection, so airbags could deploy late or not at all in a crash.

Symptoms

  • SRS or airbag warning light on or flashing
  • Several B-codes at once after bumper or front-end repair
  • Possible airbag-off indication
  • Intermittent fault that changes with vibration or moisture

Possible causes

  1. Failed front impact sensor
  2. Damaged harness on the radiator support (from a collision or repair)
  3. Corrosion or oxidation at the sensor connector
  4. Sensor missing, unplugged or mounted incorrectly after bumper work
  5. Faulty SRS module (rare)

How to diagnose

  1. Scan all SRS codes, note freeze-frame data and any companion B-codes
  2. Inspect the front sensors, their brackets and nearby body parts for collision or repair damage
  3. Check sensor connectors for moisture, corrosion, bent pins and fully seated locks
  4. Inspect the harness along the radiator support for chafing, pinching or breaks
  5. Test the sensor circuit for continuity and for shorts to ground or power
  6. Confirm the sensor type and part match the manufacturer's specification
  7. Swap in a known-good sensor, clear codes and see if the fault returns
  8. Disconnect the battery and wait the specified time before working on SRS circuits

Common fixes

  • Clean and restore connector contacts
  • Repair or replace the damaged harness section
  • Replace the front impact sensor
  • Reinstall and torque the sensor correctly after body repair
  • Replace or reprogram the SRS module if it is the cause

Questions and answers

What does B0103 mean?

The SRS module lost communication with a front impact sensor or is getting an invalid signal. Airbags may not deploy correctly in a crash.

Can I just clear the B0103 code?

Clearing only helps temporarily. If the cause remains, the code comes back, so find the problem in the sensor, connector or harness first.

Why did B0103 appear after bumper repair?

During bumper or radiator support work, a sensor connector is often left unplugged or the harness gets damaged. Check the connection and mounting of the sensor.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.