What this code means
U0104 may mean the vehicle network is not communicating properly with the driving support system control unit.
What the vehicle may do
- The vehicle may show driver support or stability-related warning messages.
- Some driver assist or stability functions may be limited while the communication fault is active.
- The fault can be intermittent if the code does not return during the confirmation check.
Possible fault areas
- Possible CAN wiring or connector issues between the VSA modulator-control unit and the multipurpose camera unit.
- Possible multipurpose camera unit software or unit-related issue.
- Possible VSA modulator-control unit software, connector terminal, or unit-related issue.
Diagnostic path
Opening context
On this 2010 to 2016 Honda CR-V with the 2.4 gas engine, U0104 means the VSA side is seeing a CAN communication failure with the driving support system control unit. In plain language, the module network may not be getting the message it expects from the driving support camera side. The vehicle may show driver support or stability-related warnings, and some assist features may not behave normally. The possible fault areas are the CAN wiring between the VSA modulator-control unit and the multipurpose camera unit, connector fit or terminal condition, module software level, or the module being tested in this path. Start with the basic system checks, then work the code in order instead of jumping straight to a module.
Confirm the code first
First, use the HDS to prove the fault is current. Turn the vehicle to ON mode, clear the DTC, turn the vehicle to OFF, then start the engine and let it idle for at least 5 seconds. Recheck for codes with the HDS. If U0104 is the only code indicated, continue with the CAN line check. If another network code is present that changes this path, diagnose that first. If U0104 does not return, treat it as an intermittent condition for now; the system is OK at this time, and if captured data is available, try to reproduce the same operating conditions before making a call.
Check the F-CAN wiring for an open
Next, check the F-CAN A_L and F-CAN A_H lines for an open between the VSA modulator-control unit and the multipurpose camera unit. Keep the vehicle in OFF mode. Disconnect the VSA modulator-control unit 38P connector and the multipurpose camera unit 20P connector. Check continuity from VSA modulator-control unit 38P connector No. 26 to multipurpose camera unit 20P connector No. 13, and from VSA modulator-control unit 38P connector No. 38 to multipurpose camera unit 20P connector No. 2. If both circuits have continuity, the wires in this part of the path are OK and you move on. If continuity is missing, repair the open in the wire between the multipurpose camera unit and the VSA modulator-control unit.
Check the multipurpose camera unit path
If the wiring continuity is good, reconnect both connectors. Then update the multipurpose camera unit, or substitute a known-good multipurpose camera unit. After that, turn the vehicle to ON mode, clear the DTC with the HDS, turn the vehicle to OFF, start the engine, and let it idle for at least 5 seconds. Check for codes again. If U0104 still comes back, continue to the VSA modulator-control unit check. If U0104 does not come back after an update, troubleshooting is complete. If the code only stays gone with a known-good substitute installed, replace the original multipurpose camera unit.
Check the VSA modulator-control unit path
If the code is still present after the camera-side check, update the VSA modulator-control unit if it does not have the latest software. Clear the DTC, turn the vehicle to OFF, start the engine, and let it idle for at least 5 seconds. Then check for codes again. If U0104 is still indicated, inspect for loose terminals at the VSA modulator-control unit 38P connector. If the VSA modulator-control unit was updated and the symptom or indication is still present, replace the VSA modulator-control unit.
Verify the repair
Keep the verification separate from the circuit and module checks. After the repair or update, clear the code, run the engine long enough for the check to run, and confirm U0104 stays gone. If U0104 is not indicated, this troubleshooting path is complete. If other codes are present afterward, check what those codes mean next. The takeaway is simple: prove the code first, verify the CAN wiring, then work through the camera-side and VSA-side checks in order. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code is often best handled by confirming whether it returns, checking the communication wiring, and then following the module update or substitution path in order.
For more guided automotive diagnostics, visit STEP Diagnostics.
