U0040Communication Bus Off
A control module has counted enough transmit errors to enter the bus-off state defined by ISO 11898 and stops transmitting on the bus. Multiple modules typically lose communication and several warning lamps illuminate at once.
Can I keep driving? NO
STOP the vehicle in a safe place. Continuing to drive may cause serious engine damage or put your safety at risk.
Sistema Afectado
Red CAN · Comunicación entre módulos
Falla de comunicación en la red CAN: pérdida de datos entre las unidades de control (ECU).
Espacio para vendedores de repuestos
Aún no hay un anunciante en este espacio.
Symptoms You Will Notice
What you may observe when this code appears
- Multiple warning lights may illuminate Affected modules may go into limp mode or shut down Specific functions inoperative depending on module Diagnostic tools may show communication faults
Possible Causes
The components or conditions that trigger this code
- 1CAN line shorted to supply or ground Terminating resistor failed Gateway module routing CAN messages incorrectly
How to Fix It — Step by Step
Recommended diagnostic and repair procedure
- 1Difficulty: hard. Estimated time: 1-6 hours. Estimated cost: €80-€
- 2Professional repair recommended
Note: This information is for general reference. For precise diagnostics and safety repairs, always consult a certified mechanic.
Estimated Cost
Approximate range in USD (varies by region and shop)
Communication modules
* Diagnosis only: $50–$150
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