Damaged or corroded wiring harness between the restraints control module and sensor D; Loose, backed-out, or corroded electrical connector at sensor D or the restraints control module; Failed restraints system sensor D itself, including internal electronics or impact sensing element; Faulty restraints control module that is not properly polling or processing sensor D data; CAN bus network fault such as a short to ground, short to power, or open circuit on the data lines; Low battery voltage or poor charging system performance causing modules to drop offline intermittently; Aftermarket accessories or improper previous repairs that disturbed the restraint system wiring

DTC codes / U01xx · Lost communication with a control module / U0173

U0173Lost Communication With 'Restraints System Sensor D'

Q: What does code U0173 mean?

Lost Communication With 'Restraints System Sensor D'. U0173 is a generic network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the restraints system sensor designated as 'D'. The computer has detected that expected periodic messages from this specific sensor have stopped arriving within the required time window, which sets the code and typically illuminates the airbag warning light.

U0173 is a generic network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the restraints system sensor designated as 'D'. The computer has detected that expected periodic messages from this specific sensor have stopped arriving within the required time window, which sets the code and typically illuminates the airbag warning light.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

Airbag or Supplemental Restraint System (SRS) warning light illuminated on the dashboard
Often no symptoms besides the warning light, with the vehicle driving normally
Other restraint-related warnings or messages displayed in the instrument cluster
Intermittent warning light that may come and go with vibration or temperature changes
Restraint system may be disabled, meaning airbags will not deploy in a collision
Multiple unrelated warning lights if the fault disrupts the entire CAN bus

Common causes, most likely first

Damaged or corroded wiring harness between the restraints control module and sensor D
Loose, backed-out, or corroded electrical connector at sensor D or the restraints control module
Failed restraints system sensor D itself, including internal electronics or impact sensing element
Faulty restraints control module that is not properly polling or processing sensor D data
CAN bus network fault such as a short to ground, short to power, or open circuit on the data lines
Low battery voltage or poor charging system performance causing modules to drop offline intermittently
Aftermarket accessories or improper previous repairs that disturbed the restraint system wiring

How to diagnose and fix it

Verify battery voltage and charging system output, as low voltage is a common cause of intermittent communication codes
Inspect the wiring and connectors at sensor D and the restraints control module for damage, corrosion, or looseness
Use a scan tool to check for other communication codes and to view live data from the restraint system sensors
Perform a resistance and continuity test on the CAN bus wiring between the restraints control module and sensor D
Check for technical service bulletins (TSBs) or software updates for the restraints control module that address communication faults
If wiring and connectors are good, substitute a known-good sensor D and clear the code to see if it returns
If the code persists after sensor replacement, diagnose or replace the restraints control module as the last step

Why U0173 is often a wiring fault

A loose or corroded connector at sensor D is far more common than a failed sensor, especially on vehicles that have had seat or trim work performed.
The code can be set by a momentary voltage drop during engine cranking, so always check for a weak battery before replacing parts.
U0173 does not always mean the sensor is dead; it can be triggered by a faulty restraints control module that fails to request data from sensor D.
Aftermarket seat covers, phone chargers, or alarm installations that tap into restraint wiring frequently cause this code to appear.
Clearing the code without repairing the underlying connection often leads to a comeback, because the fault will reset on the next drive cycle.

Can I keep driving with U0173?

The vehicle is generally safe to drive because the restraint system fault does not affect steering, braking, or engine operation, but the airbags may not deploy in a crash. Avoid rough roads and postpone long trips until the fault is repaired, and have the system diagnosed promptly to restore full safety protection.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.