What are the common causes of U0011?

Intermittent opens or shorts on the medium speed CAN. A failing transceiver on one module on the medium speed CAN. Corroded or water damaged medium speed CAN connectors. Electrical noise on the medium speed CAN.

Read the code and check module communication status on a scan tool. Monitor medium speed CAN traffic for dropped or error frames. Inspect the medium speed CAN connectors for corrosion or moisture. Check for aftermarket devices that may add noise. Replace the module that shows intermittent communication loss. Clear the code and retest.

U0011

Medium Speed CAN Communication Bus Performance

System: Network communication (U code)
Lamp: Check Engine Light
Category: Network Communications

What it means

U0011 means Medium Speed CAN Communication Bus Performance.

Check these first

Intermittent opens or shorts on the medium speed CAN
A failing transceiver on one module on the medium speed CAN
Corroded or water damaged medium speed CAN connectors
Electrical noise on the medium speed CAN

What to do next

Read the code and check module communication status on a scan tool
Monitor medium speed CAN traffic for dropped or error frames
Inspect the medium speed CAN connectors for corrosion or moisture
Check for aftermarket devices that may add noise
Replace the module that shows intermittent communication loss
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.