What this code means
U0122 may mean the acoustic vehicle alerting control unit is not receiving expected communication from the VSA modulator-control unit.
What the vehicle may do
- The vehicle may show warning messages or indicator lights.
- The acoustic vehicle alerting system may have a related concern.
- Stability-control related warnings may appear if the VSA side is also affected.
Possible fault areas
- A VSA modulator-control unit that may not be starting normally.
- A possible VSA power or ground circuit problem.
- A possible F-CAN or gateway communication issue.
Diagnostic path
Opening context
On this Accord Hybrid, U0122 means the acoustic vehicle alerting control unit may have lost communication with the VSA modulator-control unit. In plain terms, the alerting system is expecting data from the VSA unit, and when it cannot receive that data, it can set this code. The vehicle may show warning messages, may have stability-control related warnings, or may have an acoustic vehicle alerting concern, depending on what else is happening on the network. The broad fault areas to keep in mind are a VSA unit that is not starting normally, a possible VSA power or ground problem, or a possible F-CAN communication issue between modules.
Initial diagnostic order
Start with the basic system checks before going after the code directly. If there are multiple codes stored, do not chase U0122 in isolation. Sort out the network-code direction first, because another communication fault can change the path for this one.
Check the VSA unit foundation first
Before moving into the communication diagnosis, check the power and ground circuit for the VSA modulator-control unit first. That matters because this code may set if the VSA unit does not start normally, and a power or ground failure can make the acoustic vehicle alerting control unit think communication has been lost.
Network path
After the VSA power and ground side has been checked, the next diagnostic direction is the F-CAN lost-communication path for the CAN bus connection through the gateway. That is the point where the network diagnosis takes over. If that path is not available in front of you, pause, recheck the earlier diagnostic path, and avoid guessing at wiring or module replacement.
Scan tool setup
With the vehicle in ON mode, the scan tool area tied to this code is the Acoustic Vehicle Alerting System data list. Use that as the working area while you continue the communication diagnosis and confirm whether the alerting control unit is seeing the data it needs.
Repair verification
Keep verification separate from testing. Once the fault path has been handled, verify the repair and confirm the code stays gone under the same kind of operating conditions that allowed the code to set. The key takeaway is simple: for U0122, do not condemn the acoustic vehicle alerting unit first. Make sure the VSA unit can power up normally, then follow the F-CAN communication path. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code is a communication fault, so the diagnostic logic starts with module power and ground, then moves into the network communication path.
For more guided automotive diagnostics, visit STEP Diagnostics.
