Lost Communication With Restraints System Sensor C
What it means
U0172 means the airbag (SRS) system has lost communication with one of its restraints sensors — a crash/impact sensor that helps decide when to deploy. With it offline, the airbag warning light comes on and the system may not respond correctly in a collision. The engine runs normally, but this is a safety-critical fault usually caused by a wiring or connector problem, a power/ground fault, a bus fault, or a failed sensor.
Can I keep driving? Mechanically driveable, but this is a crash sensor for the airbag system — the SRS may not work correctly in a collision, so treat it as safety-critical and fix promptly.
Common symptoms
What you'll notice
- Airbag/SRS warning light on
- SRS fault stored for the restraints sensor
- Restraints system sensor C unresponsive when scanned
- No effect on how the engine runs
Common causes
Most likely first
- Wiring or connector fault to the restraints system sensorLikely
- Poor power or ground to the sensorCommon
- CAN bus fault interrupting the sensorCommon
- Failed restraints system sensorLess often
How to diagnose & fix
Work through it in order
- Scan the SRS module for related codes, following proper airbag safety precautions.
- Inspect the sensor's connector and wiring (often at a body or pillar location).
- Check the sensor's power and ground.
- Repair the wiring or replace the sensor.
- Clear codes and confirm the airbag warning light goes out.
FAQ
Quick answers
Is it safe to drive with U0172?+
Can I just clear U0172?+
Related codes
Often seen with U0172
Read & clear U0172 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.