Airbags

B0102 — Impact Sensor Circuit Malfunction

Severity: high Drive with care, to a shop

What B0102 means

The airbag (SRS) module constantly monitors impact sensors mounted in the front structure or in the doors and pillars. B0102 means the circuit of one of these sensors, on some vehicles the second one, has a fault: the signal is missing, out of range, or the sensor does not respond. The airbag system may be partly or fully disabled as a result.

Symptoms

  • Airbag/SRS warning light on or flashing
  • Airbag system disabled or working only partly
  • Fault appeared after a collision or front-end repair
  • Light may go out and return when a connection is poor

Possible causes

  1. Failed impact sensor, especially after a crash
  2. Damaged or misrouted wiring after body repair
  3. Corroded or loose sensor connector
  4. Sensor mounted loosely or in the wrong position
  5. Deformed sensor mounting point
  6. Faulty SRS control module (rare)

How to diagnose

  1. Scan the SRS module and check for other airbag codes
  2. Ask about prior collisions or body repairs and find the sensor location in the vehicle's service information
  3. Inspect the sensor for secure mounting, cracks, deformation and correct orientation
  4. Check the connector and harness for corrosion, chafing and a fully latched plug
  5. Test circuit resistance and look for shorts to ground or power per manufacturer specs
  6. Disconnect the battery and wait the specified time before working on SRS parts to avoid accidental deployment
  7. Clear the code and see whether it returns

Common fixes

  • Replace the impact sensor if it is damaged or was in a crash
  • Repair or replace the damaged wiring and connector
  • Reinstall the sensor securely in its correct position and torque
  • Straighten or repair the sensor mounting area
  • Replace the SRS module if the fault is confirmed there

Questions and answers

What does B0102 mean?

It indicates a fault in an impact sensor circuit in the airbag system. The SRS module is not getting a valid signal from that sensor.

Can I just clear B0102?

Clearing it may turn the light off briefly. If the cause remains, the code will return and the airbags may stay inoperative.

Does the sensor need replacing after a crash?

Often yes. Sensors that have taken a hard hit or been deformed are usually replaced, following the manufacturer's guidance.

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.