U0074
Control Module Communication Bus \"B\" Off
A control module has shut its bus B interface off because the bus is non-functional. Bus B is typically a secondary CAN segment (often body or chassis) and a failure disables all modules connected to it.
A control module has shut its bus B interface off because the bus is non-functional. Bus B is typically a secondary CAN segment (often body or chassis) and a failure disables all modules connected to it.
Common causes
- high
Bus B line shorted to supply or ground
One of the most commonly reported causes for this code — check this first.
Typical part cost: $90-1650
- medium
One failing module pulling the bus down
A plausible cause — test and verify before replacing parts.
Typical part cost: $90-1650
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does U0074 mean?
U0074 means "Control Module Communication Bus \"B\" Off". It is a generic OBD-II code that points to a fault in the network / communication.
What are the most common causes of U0074?
bus b line shorted to supply or ground; one failing module pulling the bus down; gateway module routing can messages incorrectly — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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