ASM Mode Circuit Range/Performance
Your engine's Antilock Brake System (ABS) Module isn't communicating properly with the main computer, like a walkie-talkie with weak batteries. The system can't verify the ABS is working correctly, so it triggers this warning.
The ECU monitors the ABS module's signal voltage and data communication over the CAN bus network. It expects steady voltage levels and valid data packets within specific timing windows. If signals fall outside normal ranges or communication drops, the fault is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| ABS Module Signal Voltage | 4.5–5.5V | Below 4.0V or above 5.8V |
| CAN Bus Message Response Time | 10–50ms intervals | Delayed or missing for >100ms |
Code P0956 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, P0956 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.