U0011

Medium Speed CAN Communication Bus Performance

Q: Is it safe to drive with U0011?

Usually yes for short trips — the medium-speed bus carries body and comfort data, not core engine control, so the car still runs. But fix it promptly, since a failing bus can knock out safety-related features too.

Q: Can I just clear U0011?

It will clear, but if the wiring or module fault is still present it returns quickly. This is a network fault that needs the physical cause repaired.

Communication network (CAN bus) Generic OBD-II Medium

What it means

U0011 is a network code: a module has detected that the medium-speed CAN bus — the data line that links body and comfort modules — is not communicating reliably. The bus is present but the data is intermittent or corrupted, usually from wiring, a bad connector, or one module dragging the network down. The engine typically still runs, but expect warning lights and glitchy body features until it's fixed.

Medium

Can I keep driving? Usually drivable — the engine still runs, but expect warning lights and some body or comfort features to act up until the bus fault is fixed.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

One or more warning lights on the dash
Body/comfort features glitch or stop working (climate, lighting, infotainment, windows)
Multiple modules set communication codes at once
Intermittent faults that come and go with vibration or temperature

Common causes

Most likely first

Corroded or loose connector on the medium-speed CAN circuitLikely
Chafed, pinched, or broken CAN wiring between modulesCommon
A single failing module loading down or corrupting the busCommon
Water intrusion into a connector or moduleLess often
Failed bus terminating resistorLess often

How to diagnose & fix

Work through it in order

Scan all modules and note every code — the pattern shows which segment of the bus is affected.
Inspect medium-speed CAN connectors and wiring for corrosion, chafing, and moisture.
Check CAN-High/CAN-Low resistance and voltages against spec to find opens or shorts.
Disconnect suspect modules one at a time to see if the bus recovers, isolating a failed module.
Repair the wiring or replace the faulty module, then clear and re-test.

FAQ

Quick answers

Is it safe to drive with U0011?+

Usually yes for short trips — the medium-speed bus carries body and comfort data, not core engine control, so the car still runs. But fix it promptly, since a failing bus can knock out safety-related features too.

Can I just clear U0011?+

It will clear, but if the wiring or module fault is still present it returns quickly. This is a network fault that needs the physical cause repaired.

Read & clear U0011 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX