What Does U0011 Mean?
The medium-speed CAN bus is operational but experiencing performance issues such as excessive error frames, slow message delivery, or intermittent communication dropouts. Data integrity or bus timing is compromised.
Common Causes
30%
Degraded or high-resistance connections in medium-speed CAN wiring causing signal reflection or attenuation
25%
Partial short to ground or voltage on one CAN wire creating imbalanced differential signal
20%
Module on network beginning to fail, sending corrupted messages or excessive error frames
15%
Incorrect or degraded terminating resistor value causing signal reflection and timing issues
10%
Electromagnetic interference from aftermarket devices or faulty components near CAN wiring
Diagnostic Steps
1
Step 1: Use oscilloscope to analyze CAN bus signal quality, looking for proper differential voltage swing (typically 2V peak-to-peak), clean edges, and absence of ringing or distortion
2
Step 2: Monitor bus error counters and network statistics using advanced diagnostic software to identify error rates and problematic modules
3
Step 3: Measure resistance between CAN High and CAN Low at multiple points along the network (should be consistent, typically 60 ohms)
4
Step 4: Check all ground connections for modules on the medium-speed network, ensuring less than 0.1 ohm resistance to chassis ground
5
Step 5: Disconnect aftermarket accessories one at a time to determine if external interference is causing performance degradation
Estimated Repair Cost
$100 - $1,500
Parts + labor, varies by vehicle and location
The medium-speed CAN bus is operational but experiencing performance issues such as excessive error frames, slow message delivery, or intermittent communication dropouts. Data integrity or bus timing is compromised.
The most common cause of U0011 (Medium Speed CAN Communication Bus Performance) is: Degraded or high-resistance connections in medium-speed CAN wiring causing signal reflection or attenuation
Typical repair costs for U0011 range from $100 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent communication issues may cause unpredictable behavior of convenience features and potential warning light illumination. Generally does not affect primary safety systems but should be repaired to prevent complete failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0011 to identify the root cause.
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Quick Info
Category
Network
System
Network Communications
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
