U0078
Control Module Communication Bus F Off
U0078 is an OBD-II diagnostic trouble code meaning: Control Module Communication Bus F Off. Common causes: broken or damaged can bus wires, oxidation or damage to connectors. Estimated repair cost: $6–56.
Symptoms
- Check Engine Light Is On
- Incorrect operation of some vehicle systems
- Lost connection with diagnostic equipment
- Dashboard malfunctions
- The car may go into emergency mode
Causes
- Broken or damaged CAN bus wires
- Oxidation or damage to connectors
- Short circuit in CAN circuit
- Malfunction of one of the control modules
- Problems with module power supply
How to Fix
- Check the integrity of the CAN bus wires
- Inspect and clean all connectors
- Check the module supply voltage
- Diagnose each module separately
- Replace damaged components
Related codes
Error U0078 by Vehicle Brand
FAQ
What does the U0078 code mean?
U0078 is an OBD-II diagnostic trouble code that indicates: Control Module Communication Bus F Off
What causes a U0078 error code?
The most common causes of U0078 include: Broken or damaged CAN bus wires; Oxidation or damage to connectors; Short circuit in CAN circuit; Malfunction of one of the control modules.
How do I fix a U0078 diagnostic trouble code?
To fix U0078: Check the integrity of the CAN bus wires. Inspect and clean all connectors. Check the module supply voltage. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U0078?
Limited driving only, diagnose soon
How much does it cost to fix U0078?
The estimated repair cost for U0078 is $6–56. Actual cost depends on your vehicle, location, and labor rates.
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