Lost Communication With Restraints System Sensor A
Your vehicle's computer has lost the ability to talk to the airbag system sensors, similar to a phone losing connection to a Bluetooth device. This is a critical safety issue that prevents airbags from deploying properly in a crash.
The ECU continuously monitors CAN bus communication with the restraints control module (RCM) to verify sensor signals and system readiness. It expects periodic heartbeat messages and valid data packets within specific time windows. Loss of communication triggers this fault when no valid restraints module messages are received for a defined duration.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| CAN Bus Communication Timeout | Valid message received every 10-100ms | No valid message for >500ms |
| Restraints Module Response | RCM responds to ECU queries | No response or corrupted data received |
Code U0170 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, U0170 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.