What Does U0013 Mean?
The CAN High wire on the medium-speed network is reading abnormally low voltage, indicating a short to ground or excessive current draw. The positive side of the differential pair cannot maintain proper voltage levels.
Common Causes
40%
CAN High wire shorted to ground due to damaged insulation or pinched harness
25%
Faulty module with internal short pulling CAN High to ground
20%
Corroded connector allowing moisture bridge between CAN High terminal and ground
10%
Failed terminating resistor or biasing circuit creating improper voltage reference
5%
Incorrect repair or modification shorting CAN High to chassis or ground circuit
Diagnostic Steps
1
Step 1: Measure voltage on CAN High wire at multiple test points with key on (should be approximately 2.5-3.5V, low reading indicates short to ground)
2
Step 2: Disconnect modules one at a time from medium-speed network while monitoring CAN High voltage to identify which module or circuit segment is causing the short
3
Step 3: Inspect wiring harness for damage, particularly where harness routes near sharp edges, ground straps, or moving components
4
Step 4: Check for liquid intrusion in connectors and junction boxes that could create ground path
5
Step 5: Measure resistance from CAN High to ground with all modules disconnected (should be high resistance >10k ohms, low resistance confirms short)
Estimated Repair Cost
$150 - $1,400
Parts + labor, varies by vehicle and location
The CAN High wire on the medium-speed network is reading abnormally low voltage, indicating a short to ground or excessive current draw. The positive side of the differential pair cannot maintain proper voltage levels.
The most common cause of U0013 (Medium Speed CAN Communication Bus (+) Low) is: CAN High wire shorted to ground due to damaged insulation or pinched harness
Typical repair costs for U0013 range from $150 to $1,400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Primarily affects comfort and convenience features on medium-speed network. Vehicle is generally safe to operate but may experience inoperative body control functions and multiple warning lights.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0013 to identify the root cause.
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Quick Info
Category
Network
System
Network Communications
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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