What this code means
U0029 may indicate a CAN communication failure related to the VSA control unit, where network communication can become unreliable or drop out.
What the vehicle may do
- The vehicle may show stability or traction-related warning behavior.
- Some VSA-related functions may be limited while the communication fault is active.
- Scan tool results may point toward a network communication issue rather than a single mechanical fault.
Possible fault areas
- Possible CAN wiring concerns between the PCM and VSA modulator-control unit.
- Possible loose terminals or poor connections at the involved control unit connectors.
- Possible VSA modulator-control unit software concern.
- Possible VSA modulator-control unit concern after the supported checks are completed.
Diagnostic path
Open with the code logic
On this CR-V, U0029 is a CAN communication failure seen in the VSA control unit. In plain language, the stability system may be losing reliable network communication, and the vehicle may show stability or traction-related warning behavior. The possible fault areas can include the CAN wiring between the PCM and the VSA modulator-control unit, connector condition at those units, VSA software, or the VSA unit itself. Before getting deep into this code path, start with the basic system checks. If PGM-FI codes are present, handle those first, because engine-management faults can affect how this diagnosis plays out.
Verify the failure first
Start by verifying the problem. Turn the vehicle to ON mode, clear the DTC with the HDS, then turn the vehicle to OFF, or LOCK, mode and start the engine. Wait 2 seconds or more, then check for DTCs again with the HDS. If U0029-00 is indicated, the failure is duplicated and you move into the CAN line check. If U0029-00 is not indicated, treat it as an intermittent failure. The system is OK at this time, and if captured conditions or an on-board snapshot are available, try to reproduce the failure under those same conditions instead of guessing.
Check the F-CAN lines for an open
Next is the open-wire check on the F-CAN high and F-CAN low circuits. Turn the vehicle to OFF, or LOCK, mode. Jump the SCS line with the HDS and wait more than 1 minute. Then disconnect the VSA modulator-control unit 38P connector and PCM connector A, the 51P connector. Check continuity from VSA connector terminal No. 38 to PCM connector A terminal No. 2, and from VSA connector terminal No. 26 to PCM connector A terminal No. 1. If there is continuity, the F-CAN high and F-CAN low wires are OK, so continue to the VSA modulator-control unit check. If there is no continuity, repair the open in the wire between the PCM and the VSA modulator-control unit.
Update and recheck the VSA unit
With the wiring check passed, reconnect the VSA modulator-control unit 38P connector and PCM connector A, the 51P connector. Update the VSA modulator-control unit if it does not have the latest software. Then turn the vehicle to OFF, or LOCK, mode, start the engine, wait 2 seconds or more, and check for DTCs with the HDS. If U0029-00 is still indicated, check for loose terminals and poor connections 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
After the wiring repair, connector correction, software update, or supported module replacement, verify the repair and confirm the code stays gone. If U0029-00 is not indicated, this troubleshooting path is complete. If other codes are still present, check what they mean next. The takeaway is simple: verify the code, prove the CAN wiring between the PCM and VSA unit, then only move into VSA software, connector, and unit decisions after the network path checks out. For more diagnostic training, visit stepdiagnostics.com.
Final check
U0029 is best approached by verifying the fault first, checking the CAN wiring path, then moving to VSA software, connector condition, and supported unit decisions only after the communication circuit
For more guided automotive diagnostics, visit STEP Diagnostics.
