What Does U0172 Mean?
The airbag control module has lost network communication with restraint system sensor C. This disruption prevents proper crash detection and airbag deployment timing for the affected sensor zone.
Safety Warning
Airbag system functionality is severely compromised and may not provide adequate occupant protection during collision. Vehicle is unsafe to operate until repaired.
Common Causes
35%
Failed impact sensor C due to internal component failure or moisture damage
30%
Broken or damaged wiring between sensor C and the airbag control module
20%
Poor ground connection or corroded ground terminal at sensor C location
10%
CAN network fault affecting sensor C communication path (bus fault or termination issue)
5%
Airbag control module malfunction in sensor C communication circuit
Diagnostic Steps
1
Step 1: Identify sensor C location from vehicle-specific wiring diagram and inspect sensor mounting, connector condition, and surrounding area for damage
2
Step 2: Measure voltage at sensor C connector for proper 5V reference supply and verify ground circuit has less than 0.1V resistance to chassis
3
Step 3: Test CAN high and CAN low signal wires for proper resistance (60-120 ohms between them) and check for shorts to power or ground
4
Step 4: Wiggle test wiring harness while monitoring communication status to identify intermittent connection failures
5
Step 5: Substitute sensor C with known-good unit if all electrical tests pass to confirm sensor internal failure
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The airbag control module has lost network communication with restraint system sensor C. This disruption prevents proper crash detection and airbag deployment timing for the affected sensor zone.
The most common cause of U0172 (Lost Communication With Restraints System Sensor C) is: Failed impact sensor C due to internal component failure or moisture damage
Typical repair costs for U0172 range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Airbag system functionality is severely compromised and may not provide adequate occupant protection during collision. Vehicle is unsafe to operate until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0172 to identify the root cause.
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Quick Info
Category
Network
System
Supplemental Restraint System (SRS/Airbag)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
