What Does U0025 Mean?
The negative (-) line of the low-speed CAN bus voltage is reading lower than specification. This indicates the CAN- circuit is shorted to ground or a module is pulling the line low.
Common Causes
35%
CAN- wire shorted to ground in wiring harness
30%
Failed module with internal short to ground on CAN- circuit
15%
Water damage causing short to ground in connector
15%
Pinched harness at body or frame mounting point
5%
Faulty aftermarket accessory tied into CAN network
Diagnostic Steps
1
Step 1: Measure voltage on CAN- line with key on; voltage below 2.0V indicates low condition
2
Step 2: Check resistance from CAN- to ground with all modules disconnected (should be infinite resistance)
3
Step 3: Disconnect modules one by one and recheck resistance to identify faulty module causing short
4
Step 4: Inspect harness routing for pinch points, particularly where harness passes through body panels or near sharp edges
5
Step 5: Test for intermittent shorts by wiggling harness while monitoring voltage or resistance
Estimated Repair Cost
$150 - $850
Parts + labor, varies by vehicle and location
The negative (-) line of the low-speed CAN bus voltage is reading lower than specification. This indicates the CAN- circuit is shorted to ground or a module is pulling the line low.
The most common cause of U0025 (Low Speed CAN Communication Bus (-) Low) is: CAN- wire shorted to ground in wiring harness
Typical repair costs for U0025 range from $150 to $850, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Network malfunction may cause warning lights, loss of gauge functions, or disabled safety features. Vehicle may enter reduced functionality mode.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0025 to identify the root cause.
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Quick Info
Category
Network
System
Network Communications
Difficulty
Type
Generic (SAE)
Recommended Tools
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