Airbags

B0073 — Second Row Left Seatbelt Pretensioner Deployment Circuit Fault

Severity: medium Safe to drive

What B0073 means

The SRS (airbag) control module continuously tests the squib circuit of the rear left seatbelt pretensioner for resistance, opens and shorts. B0073 is set when that circuit falls outside its expected range. The system may then disable that pretensioner, so it would not fire in a crash.

Symptoms

  • SRS / airbag warning light is on
  • Dashboard message or chime about a restraint system fault
  • No change in engine or transmission performance
  • Pretensioner may not fire in a collision

Possible causes

  1. Damaged wiring or connector: open, short or corrosion
  2. Failed second row left seatbelt pretensioner
  3. Poor connection at the connector under the rear seat or in the body pillar, often after interior work or seat removal
  4. Communication problem or internal fault in the SRS module
  5. Software or calibration error in the SRS module (rare)

How to diagnose

  1. Scan all codes with a tool that supports SRS and review freeze frame data to see if the fault is constant or intermittent
  2. Inspect the connector and wiring near the rear left belt and under the seat for moisture, corrosion and chafing
  3. Ask about recent collision repair, interior work or seat removal that could have damaged the harness
  4. Follow the manufacturer's SRS safety procedure (disconnect the battery and wait) before touching any airbag connectors
  5. Never probe a squib circuit with a standard multimeter; use proper SRS test equipment or scan tool data to check circuit resistance
  6. Where the manufacturer allows, swap in a known good pretensioner or a test load to isolate the fault
  7. Check the SRS module for software updates and internal faults
  8. Clear the code and confirm it does not return

Common fixes

  • Repair or replace damaged wiring and connectors
  • Replace the faulty seatbelt pretensioner
  • Update or reflash the SRS module software
  • Replace the SRS module if it is confirmed faulty

Questions and answers

Can I drive with code B0073?

Yes, the car will drive normally because the fault does not affect the engine or brakes. But the rear left pretensioner may not work in a crash, so get it repaired soon.

Can I test the pretensioner circuit myself?

You can read the code and visually inspect the connectors. Do not test the squib circuit with a regular multimeter, as that risks an accidental deployment. Leave measurements to a qualified technician.

Why did B0073 come back after clearing it?

The fault is most likely still present, such as a poor connection, a broken wire or a bad pretensioner. The SRS light will keep returning until the cause is fixed.

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.