U0170 indicates that the vehicle's control network has lost communication with a restraints system sensor, such as an occupant detection, seat‑belt pretensioner, or side‑impact sensor. The airbag or restraints control module can no longer receive data from that sensor, which triggers a warning light and stores the fault code.
The sensor itself (e.g., occupant detection, seat‑belt pretensioner, or side‑impact sensor) has failed internally, preventing it from transmitting data on the CAN bus.
Harness chafing, corrosion, loose pins, or broken wires between the sensor and the restraints module can interrupt the signal.
The module that monitors the sensors may have an internal communication fault, causing it to lose contact with one or more sensors.
Problems with the CAN bus—such as missing termination resistors, shorted bus lines, or excessive electromagnetic interference—can prevent the sensor's messages from reaching the module.
Although the powertrain control module is not part of the restraints network, a severe CAN bus fault affecting the PCM could indirectly trigger U0170; this is uncommon and should be considered only after other causes are ruled out.
No. The PCM/ECM is not part of the restraints communication network. Replacing it will not resolve a lost‑sensor communication fault unless a rare, widespread CAN bus failure is present, which should be diagnosed first.
A loose buckle itself does not trigger U0170, but if the seat‑belt pretensioner or its sensor is damaged or unplugged due to buckle movement, it can lead to the code.
The system may disable the affected sensor’s circuit, which can prevent the related airbag or pretensioner from deploying. It is important to repair the fault to ensure full restraints functionality.
While the vehicle may still drive, the restraints system may be compromised. Repair should be performed promptly to maintain crash safety.