U0172: Lost Communication With Restraints System Sensor C

What it means

The reporting module has lost communication with Restraints System Sensor C. It sets this code when expected sensor messages are not received for a specified time.

How it works

Restraints System Sensor C supplies crash or restraint-related information to the vehicle’s restraint system over a communication network. U0172 sets when the reporting module misses the expected messages from Sensor C for the required time.

Common causes

Most likely first.

1. Sensor C power or ground fault
2. Damaged or corroded sensor wiring or connectors
3. CAN bus fault
4. Restraints sensor C failure
5. Low battery voltage

Symptoms

• Airbag warning light
• Restraint system warning message
• Airbags or pretensioners may be unavailable

How to diagnose it

1. Scan restraint and related modules for additional communication codes, and preserve any event or freeze-frame data.
2. Review battery and charging condition for low voltage around the time the fault was recorded.
3. Using the manufacturer's restraint-system safety procedure, inspect Sensor C’s connector and wiring for looseness, corrosion, or physical damage.
4. Check Sensor C’s power and ground against the manufacturer's specification.
5. If those circuits are sound, test the communication wiring and network before concluding that Sensor C has failed.

Common fixes

• Repair a weak battery or poor battery connection if voltage is low.
• Reconnect or repair the Sensor C connector and harness.
• Restore Sensor C’s power or ground supply.
• Repair a communication network fault or replace Sensor C if testing isolates the failure to that sensor.

Can I keep driving?

Some restraint functions, including airbags or pretensioners, may be unavailable while this fault is active. Avoid unnecessary driving and have the system checked promptly, following proper safety procedures for restraint wiring.