This code indicates that a control module on the vehicle's network has lost communication with a specific sensor in the restraints (airbag/safety) system, designated as Sensor D. It is a network/communication fault, not a direct indication that an airbag has failed or deployed. The vehicle's restraint control module cannot exchange data with that sensor, which may disable certain safety functions.
Open circuits, chafed wires, corroded pins, or loose connectors in the communication circuit between the restraint control module and Sensor D are the most common cause of this code.
The sensor itself may have failed internally and stopped responding on the communication bus. This is plausible only after wiring and connector integrity are confirmed.
The module that manages the restraints network could have an internal communication driver failure, though this is far less common than wiring or sensor faults.
A broader network issue such as bus wiring damage, termination resistance problems, or a short on the communication line could prevent the sensor from communicating.
The engine computer is extremely unlikely to cause this code. The PCM is not the communicating partner for restraint sensors, and replacing it would not resolve a restraints network communication loss.
Driving is not recommended. This code involves the restraints system, and certain airbag or pretensioner functions may be disabled, reducing occupant protection in a crash.
No. The PCM is not responsible for communication with restraints system sensors. Replacing it will not resolve this code and is a misdiagnosis. The issue lies in the restraint system wiring, the sensor itself, or the restraint control module.
A severely low or unstable battery voltage can sometimes cause intermittent module communication faults, but U0173 typically points to a dedicated wiring or sensor problem in the restraints circuit rather than a general power issue.
No. This code means communication with a restraint sensor is lost, which typically disables that sensor's function rather than causing unintended deployment. However, it does mean the restraint system may not operate correctly in a collision.