What Does U0022 Mean?
The positive (+) line of the low-speed CAN bus is experiencing a voltage that is lower than specification. This indicates a short to ground or loss of termination resistance on the CAN+ circuit.
Common Causes
35%
Damaged wiring harness with CAN+ wire shorted to ground
25%
Failed module pulling CAN+ bus voltage low
20%
Corroded or damaged connector terminals causing resistance
15%
Faulty termination resistor or missing termination
5%
Water intrusion in harness or module causing short
Diagnostic Steps
1
Step 1: Measure voltage on CAN+ line at diagnostic port with key on; should read approximately 2.5V (idle state)
2
Step 2: Disconnect modules one at a time on low-speed CAN network to isolate faulty module pulling voltage low
3
Step 3: Inspect all accessible CAN bus connectors for corrosion, bent pins, or moisture intrusion
4
Step 4: Check resistance between CAN+ and ground with all modules disconnected; should read infinite resistance
5
Step 5: Trace wiring harness for pinch points, damage, or areas where insulation may be compromised
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The positive (+) line of the low-speed CAN bus is experiencing a voltage that is lower than specification. This indicates a short to ground or loss of termination resistance on the CAN+ circuit.
The most common cause of U0022 (Low Speed CAN Communication Bus (+) Low) is: Damaged wiring harness with CAN+ wire shorted to ground
Typical repair costs for U0022 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience loss of convenience features, warning lights, or intermittent starting issues. Multiple systems may malfunction due to communication loss.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0022 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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